Abu Huraira reported: A man came to the Prophet and he said, “Advise me.” The Prophet, peace and blessings be upon him, said, “Do not be angry.” The man repeated his request and the Prophet said, “Do not be angry.”
Source: Ṣaḥīḥ al-Bukhārī 6116
Grade: Sahih (authentic) according to Al-Bukhari
عَنْ أَبِي هُرَيْرَةَ أَنَّ رَجُلًا قَالَ لِلنَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَوْصِنِي قَالَ لَا تَغْضَبْ فَرَدَّدَ مِرَارًا قَالَ لَا تَغْضَبْ
6116 صحيح البخاري كتاب الأدب باب الحذر من الغضب