Tolerance means that one should be practiced to bear insult and dishonor from others. If one is engaged in the advancement of spiritual knowledge, there will be so many insults and much dishonor from others. This is expected because material nature is so constituted. Even a boy like Prahlāda, who, only five years old, was engaged in the cultivation of spiritual knowledge, was endangered when his father became antagonistic to his devotion. The father tried to kill him in so many ways, but Prahlāda tolerated him. So there may be many impediments to making advancement in spiritual knowledge, but we should be tolerant and continue our progress with determination.
(Bhagavad-Gita--13:8-12--purport).

When we speak of a living entity, we must see the body and the mind as two outward coverings, two layers of paraphernalia—and the living force or spirit soul as the chief, central figure. The outward coverings are temporary arrangements, and therefore everything dependent on the outward covering is also a temporary arrangement. Happiness or distress perceived in relation with the temporary arrangement of the body and mind is also temporary. Thus, in Bhagavad-gītā the Personality of Godhead, Śrī Kṛṣṇa, says, "O son of Kuntī! All forms of happiness or distress, such as winter cold or summer heat, are due to material sense perception only. They come and go according to the laws of nature, and they are therefore to be tolerated without our being disturbed. One who is not disturbed by all these comings and goings of temporary happiness and distress—he alone becomes a fit person to attain eternal life."
(Message of godhead).

"One who seeks Your compassion and thus tolerates all kinds of adverse conditions due to the karma of his past deeds, who engages always in Your devotional service with his mind, words and body, and who always offers obeisances unto You, is certainly a bona fide candidate for liberation." A devotee who tolerates everything in this material world and patiently executes his devotional service can become mukti-pade sa dāya-bhāk, a bona fide candidate for liberation. The word dāya-bhāk refers to a hereditary right to the Lord's mercy. A devotee must simply engage in devotional service, not caring about material situations. Then he automatically becomes a rightful candidate for promotion to Vaikuṇṭhaloka. The devotee who renders unalloyed service to the Lord gets the right to be promoted to Vaikuṇṭhaloka, just as a son inherits the property of his father.
(Srimad Bhagavatam--8:4:13--purport).

While engaged in preaching work, he has to meet with so many opposing elements, and therefore the sādhu, or devotee of the Lord, has to be very tolerant. Someone may ill-treat him because the conditioned souls are not prepared to receive the transcendental knowledge of devotional service. They do not like it; that is their disease. The sādhu has the thankless task of impressing upon them the importance of devotional service. Sometimes devotees are personally attacked with violence. Lord Jesus Christ was crucified, Haridāsa Ṭhākura was caned in twenty-two marketplaces, and Lord Caitanya's principal assistant, Nityānanda, was violently attacked by Jagāi and Mādhāi. But still they were tolerant because their mission was to deliver the fallen souls. One of the qualifications of a sādhu is that he is very tolerant and is merciful to all fallen souls. He is merciful because he is the well-wisher of all living entities. He is not only a well-wisher of human society, but a well-wisher of animal society as well.
(Srimad Bhagavatam-3:25:21).