Rabi, the paternal aunt of Anas, broke the front tooth of a young girl. The family of the girl was asked to pardon the offense, but they refused. They then came to the Messenger of Allah ﷺ, who said, "Retaliation is required."Anas bin Nadr said, "Messenger of Allah, will the front tooth of so-and-so be broken?"The Messenger of Allah ﷺ replied, "Anas, the Book of Allah requires retaliation."Anas bin Nadr said, "By the One who sent you with the truth, her front tooth shall not be broken."The family then accepted compensation, pardoned the offense, and waived the retaliation.The Messenger of Allah ﷺ said, "Indeed, among the servants of Allah are those who, if they were to swear an oath by Allah, He would fulfill it for them."
حدثنا ابن أبي عدي عن حميد
أن الربيع عمة أنس كسرت ثنية جارية فطلبوا إلى القوم العفو فأبوا فأتوا رسول الله ﷺ فقال القصاص قال أنس بن النضر يا رسول الله تكسر ثنية فلانة فقال رسول الله ﷺ يا أنس كتاب الله القصاص قال فقال والذي بعثك بالحق لا تكسر ثنية فلانة قال فرضي القوم فعفوا وتركوا القصاص فقال رسول الله ﷺ إن من عباد الله من لو أقسم على الله أبره
Its isnad is sahih. It is found in Bukhari 5/306, no. 2703, in Fath al-Bari, in the chapter on reconciliation, "Reconciliation regarding blood money", and in Muslim 3/1302, no. 1675, in the chapter on qasamah, "Establishing retaliation", and in Nasai 8/27, no. 4756, with similar wording, and in Ibn Majah 2/884, no. 2649, in the chapter on blood money, "Retaliation for a tooth".