We pledged allegiance to the Messenger of Allah ﷺ to hear and obey, and he said, "To the best of your ability."
حدثنا علي بن محمد حدثنا وكيع حدثنا شعبة عن عتاب مولى هرمز قال سمعت
بايعنا رسول الله ﷺ على السمع والطاعة فقال فيما استطعتم
[Its isnad is hasan] Ahmad reported it: 3/120, Atraf Musnad: 1/444, from Waki with this chain, and it is in Musnad Tayalisi, no. 2083, from Shubah with this chain.