Am I sinful if I do not repeat advice to a person who committed a mistake in front of me and whom I warned against it, then he returned to it again, especially with people currently being annoyed by guidance, and fearing that this would lead to their dislike of speaking with me?

A Muslim's sincere advice to his brother and his denunciation of evil are obligatory when a sin is repeated. This must be done with gentleness, wisdom, and admonition, using various means of persuasion, such as lending beneficial tapes and رسائل (epistles/messages), seeking advice from those whose counsel influences the person, and praying for their guidance.

It is also necessary to endear oneself to family members through good manners and kind treatment, and to be patient with the presence of objectionable pictures in the home, without tearing them up before they are convinced [to remove them]. Indeed, the Prophet, peace and blessings be upon him, was patient with idols in his house until the Conquest.

Furthermore, a Muslim woman should continue seeking knowledge, reciting the Qur'an, studying books of Hadith and سیر (biographies), associating with committed sisters, and avoiding idle gatherings. For Allah rewards the sincere caller, even if those called do not benefit.