In Manu-saṁhitā, the lawbook for mankind, it is supported that a murderer should be condemned to death so that in his next life he will not have to suffer for the great sin he has committed. Therefore, the king's punishment of hanging a murderer is actually beneficial. Similarly, when Kṛṣṇa orders fighting, it must be concluded that violence is for supreme justice, and thus Arjuna should follow the instruction, knowing well that such violence, committed in the act of fighting for Kṛṣṇa, is not violence at all because, at any rate, the man, or rather the soul, cannot be killed; so for the administration of justice, so-called violence is permitted.
(Bhagavad-Gita-----2:21-----purport).

Lord Caitanya said that a teacher should behave properly before he begins teaching. One who teaches in that way is called ācārya, or the ideal teacher. Therefore, a teacher must follow the principles of śāstra (scripture) to teach the common man. The teacher cannot manufacture rules against the principles of revealed scriptures. The revealed scriptures, like Manu-saṁhitā and similar others, are considered the standard books to be followed by human society. Thus the leader's teaching should be based on the principles of such standard śāstras. One who desires to improve himself must follow the standard rules as they are practiced by the great teachers.
(Bhagavad-Gita-----3:21-----purport).

It is said in the Manu-smṛti that lust cannot be satisfied by any amount of sense enjoyment, just as fire is never extinguished by a constant supply of fuel. In the material world, the center of all activities is sex, and thus this material world is called maithunya-āgāra, or the shackles of sex life.
(Bhagavad-Gita-----3:39-----purport).

The ten processes of reformatory ceremonies, as enjoined in the Manu-smṛti, which is the guide to religious principles, are meant for reviving God consciousness in the system of varṇāśrama. However, no process is strictly followed now in any part of the world, and therefore 99.9 percent of the population is narādhama.
(Bhagavad-Gita-----7:15-----purport).

The demons are not clean, either externally or internally. One should always be careful to keep his body clean by bathing, brushing teeth, shaving, changing clothes, etc. As far as internal cleanliness is concerned, one should always remember the holy names of God and chant Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare/ Hare Rāma, Hare Rāma, Rāma Rāma, Hare Hare. The demons neither like nor follow all these rules for external and internal cleanliness.
As for behavior, there are many rules and regulations guiding human behavior, such as the Manu-saṁhitā, which is the law of the human race. Even up to today, those who are Hindu follow the Manu-saṁhitā. Laws of inheritance and other legalities are derived from this book. Now, in the Manu-saṁhitā it is clearly stated that a woman should not be given freedom. That does not mean that women are to be kept as slaves, but they are like children. Children are not given freedom, but that does not mean that they are kept as slaves. The demons have now neglected such injunctions, and they think that women should be given as much freedom as men.
(Bhagavad-Gita-----16:7-----purport).

Actually, a woman should be given protection at every stage of life. She should be given protection by the father in her younger days, by the husband in her youth, and by the grownup sons in her old age. This is proper social behavior according to the Manu-saṁhitā. But modern education has artificially devised a puffed—up concept of womanly life, and therefore marriage is practically now an imagination in human society.
(Bhagavad-Gita-----16:7-----purport).

In modern days the people in general occupy the administration by the strength of manipulated votes, but they are never trained in the primary duties of the king, and that is also not possible for everyone. Under the circumstances the untrained administrators play havoc to make the subjects happy in all respects. On the other hand, these untrained administrators gradually become rogues and thieves and increase the taxation to finance a top-heavy administration that is useless for all purposes. Actually the qualified brāhmaṇas are meant to give direction to the kings for proper administration in terms of the scriptures like the Manu-saṁhitā and Dharma-śāstras of Parāśara.
(Srimad Bhagavatam-----1:9:27-----purport).

In the Manu-smṛti it is recommended that by offerings of sacrifice on the altar of the fire, the sun-god is pleased. When the sun-god is pleased, he properly collects water from the sea, and thus sufficient clouds collect on the horizon and rains fall. After sufficient rains fall, there is sufficient production of grains for men and all animals, and thus there is energy in the living being for progressive activity.
(Srimad Bhagavatam-----1:16:20-----purport).

The Manu-saṁhitā is the standard lawbook for humanity, and every human being is advised to follow this great book of social knowledge.
(Srimad Bhagavatam-----2:1:36-----purport).

The kings or the kṣatriya administrators would always consult the council of learned brāhmaṇas. They were never autocratic monarchs. The scriptures like Manu-saṁhitā and other authorized books of the great sages were guiding principles for ruling the subjects, and there was no need for less intelligent persons to manufacture a code of law in the name of democracy. The less intelligent mass of people have very little knowledge of their own welfare, as a child has very little knowledge of its future well-being. The experienced father guides the innocent child towards the path of progress, and the childlike mass of people need similar guidance. The standard welfare codes are already there in the Manu-saṁhitā and other Vedic literatures. The learned brāhmaṇas would advise the king in terms of those standard books of knowledge and with reference to the particular situation of time and place.
(Srimad Bhagavatam-----2:7:9-----purport).

The lawbook for the entire human society is the Manu-saṁhitā, which directs all activities towards the transcendental service of the Lord. Every king, therefore, must know that his responsibility in administration is not merely to exact taxes from the citizens but to see personally that the citizens under him are being trained in Viṣṇu worship. Everyone must be educated in Viṣṇu worship and engaged in the devotional service of Hṛṣīkeśa, the owner of the senses.
(Srimad Bhagavatam-----3:13:12-----purport).

To give a daughter in charity to a suitable son-in-law is considered to be one of the pious activities of a householder. There are eight forms of marriage mentioned in the scripture Manu-smṛti, but only one process of marriage, brāhma or rājasika marriage, is now current. Other kinds of marriage-by love, by exchange of garlands or by kidnapping the bride-are now forbidden in this Kali age.
(Srimad Bhagavatam-----3:22:16-----purport).

According to Manu-saṁhitā, a woman is never independent. She must remain the property of the father while she is not married, and she must remain the property of the husband until she is elderly and has grown-up children of her own.
(Srimad Bhagavatam-----3:22:25-----purport).

According to Manu, women, the fair sex, should not have independence at any stage of life. In childhood a woman must be under the protection of the parents, in youth she must be under the protection of the husband, and in old age she must be under the protection of the grown children. Devahūti demonstrated all these statements of the Manu-saṁhitā in her life: as a child she was dependent on her father, later she was dependent on her husband, in spite of her opulence, and she was later on dependent on her son, Kapiladeva.
(Srimad Bhagavatam-----3:33:19-----purport).

According to Manu-smṛti, one should never desert his wife and children. In a case where the wife and children are disobedient and do not follow the principles of home life, they are sometimes given up.
(Srimad Bhagavatam-----4:8:65-----purport).

In Bhakti-rasāmṛta-sindhu, Śrīla Rūpa Gosvāmī says that if one poses himself as advanced in spiritual life but does not refer to the śrutis and smṛtis he is simply a disturbance in society. One should follow the principles laid down in śrutis and smṛtis not only in one's spiritual life but in material life as well. As far as human society is concerned, it should follow the Manu-smṛti as well, for these laws are given by Manu, the father of mankind.
(Srimad Bhagavatam-----4:18:3-----purport).

In the Manu-smṛti it is stated that a woman should not be given independence, but should be given protection by her father, husband and elderly sons. In all circumstances a woman should remain dependent upon some guardian. Presently women are given full independence like men, but actually we can see that such independent women are no happier than those women who are placed under guardians. If people follow the injunctions given by the great sages, śrutis and smṛtis, they can actually be happy in both this life and the next.
(Srimad Bhagavatam-----4:18:3-----purport).

In Manu-saṁhitā it is stated that it is necessary for a king to execute a murderer so that the murderer will not suffer for his criminal actions in his next life. On the basis of such understanding, Nārada Muni warns the King that the animals killed in sacrifices by the King await him at his death in order to avenge themselves. Nārada Muni is not contradicting himself here. Nārada Muni wanted to convince the King that overindulgence in animal sacrifice is risky because as soon as there is a small discrepancy in the execution of such a sacrifice, the slaughtered animal may not be promoted to a human form of life. Consequently, the person performing sacrifice will be responsible for the death of the animal, just as much as a murderer is responsible for killing another man.
(Srimad Bhagavatam-----4:25:8-----purport).

Every woman is fond of children; therefore any husband who can please his wife by sex and give her children is considered very magnanimous. Not only does the husband become magnanimous by begetting children, but by giving his wife ornaments, nice food and dresses, he keeps her completely under submission. Such a satisfied wife will never give up the company of her husband. Manu-saṁhitā recommends that to keep a wife satisfied a husband should give her some ornaments because women are generally fond of home, ornaments, dresses, children, etc. In this way the woman is the center of all material enjoyment.
(Srimad Bhagavatam-----4:25:41-----purport).

The punishment awarded by the state or by God for one's own faults is actually for one's benefit. In the Manu-saṁhitā it is said that the King should be considered merciful when he condemns a murderer to death because a murderer punished in this life becomes freed from his sinful activity and in the next life takes birth cleared of all sins. If one accepts punishment as a reward dealt by the master, he becomes intelligent enough not to commit the same mistake again.
(Srimad Bhagavatam-----4:26:21-----purport).

A man is allowed to keep more than one wife because he cannot enjoy sex when the wife is pregnant. If he wants to enjoy sex at such a time, he may go to another wife who is not pregnant. These are laws mentioned in the Manu-saṁhitā and other scriptures.
(Srimad Bhagavatam-----4:27:5-----purport).