Abu Aiyub (RAA) narrated that the Messenger of Allah (ﷺ) said:
"It is not permissible for a Muslim to shun his brother for more than three nights. When they meet, this one turns away (from that one) and that one turns away (from this one) and the best of them is the one who greets his brother first." Agreed upon
English reference: Book 16, Hadith 1504
Arabic reference: Book 16, Hadith 1461