Muwatta Malik 1808

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, may Allah bless him and grant him peace, said to us, 'In what you are able

Reference

Muwatta Malik 1808

In-book

Book 55, Hadith 1