مُوَطَّأُ مَالِكٍ
Muwatta Malik 1811
The Oath of Allegiance
حَدَّثَنِي مَالِكٌ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، قَالَ كُنَّا إِذَا بَايَعْنَا رَسُولَ اللَّهِ صلى الله عليه وسلم عَلَى السَّمْعِ وَالطَّاعَةِ يَقُولُ لَنَا رَسُولُ اللَّهِ صلى الله عليه وسلم فِيمَا اسْتَطَعْتُمْ .
Malik related to me from Abdullah ibn Dinar that Abdullah ibn Umar said, "When we took an oath of allegiance with him to hear and obey, the Messenger of Allah, (ﷺ), said to us, 'In what you are able.' "
Arabic/English book reference: Book 55, Hadith 1