Riyad as-SalihinChapter 17Hadith 913
Full Sharh — Riyad as-Salihin 913
وعن أبي أيوب رضي الله عنه أن رسول الله صلى الله عليه وسلم قال: "لا يحل لمسلم أن يهجر أخاه فوق ثلاث ليال: يلتقيان، فيعرض هذا ويعرض هذا، وخيرهما الذي يبدأ بالسلام" ((متفق عليه)).
English Translation
Abu Ayyub Al-Ansari (May Allah be pleased with him) said:: The Messenger of Allah (ﷺ) said, "It is not lawful for a Muslim to desert (stop talking to) his brother beyond three nights, the one turning one way and the other turning to the other way when they meet, the better of the two is one who is the first to greet the other.".
Source
Riyad as-Salihin(رياض الصالحين)
The Book of the Prohibited actions
Hadith Number
913