آداب السلام والاستئذان
Abu Ayyūb al-Ansāri (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: "It is unlawful for a Muslim to desert his fellow Muslim for more than three nights. As they meet, both of them turn their backs on each other. However, the best of them is the one who starts by greeting the other.”
عن أبي أيوب الأنصاري -رضي الله عنه- قال: قال رسول الله -صلى الله عليه وسلم-: «لا يحل لمسلم أن يهجر أخاه فوق ثلاث ليال، يلتقيان: فيُعرض هذا، ويُعرض هذا، وخيرهما الذي يبدأ بالسلام».
شرح الحديث :
The Hadīth forbids deserting one's fellow Muslim for more than three nights. On meeting, they both turn their backs on each other without greeting or speaking to each other. This Hadīth implies that one may desert his fellow Muslim for three days or less, thereby allowing one to vent his accidental anger. It is part of the human nature to feel angry. The kind of desertion intended in this Hadīth is what one practices for his own sake. However, one may desert for the sake of Allah, the Almighty, like deserting sinners, heretic innovators and bad companions. This does not have a time limit. It is rather contingent on a cause, and such a desertion will stop the time that cause ceases to exist. The best among these two who are on bad terms with each other is the one who tries to reconcile with the other and starts by greeting him.