[1]
Narrated Abu Hurairah (RA) that the Messenger of Allah (PBUH) said: “On Mondays and Thursdays, the gates of Paradise are opened. Then every person is forgiven except one who harbors enmity with his brother. It is said regarding them: Give them respite until they agree to reconcile with each other.” (Sahih Muslim, 4658)
[2]
Narrated Hisham ibn ‘Amr (RA) that the Messenger of Allah (PBUH) said: “It is not permissible for a Muslim to cut off relations with his Muslim brother for more than three days. For if they remain in this state for more than three days, they remain distant from the truth. Whoever initiates reconciliation first, it counts as expiation for him. And if one greets the other but the other does not reply, angels will greet the one who greeted, and Satan will greet the one who did not respond. And if both die while in this state of severed relations, neither of them will enter Paradise.” (Musnad Ahmad, 15917)
[3]
Whoever keeps severed relations with his brother for more than three days will enter Hell, except that Allah, by His special grace, looks upon him with mercy. (Musannaf Ibn Abi Shaybah, 24786)