It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that Sayyidah al-Rubayyi' bint al-Nadr (may Allah be pleased with her) slapped a girl of the Ansar and broke her front tooth. So they came to the Prophet (peace and blessings be upon him) and demanded retaliation (qisas). Anas bin al-Nadr (may Allah be pleased with him) said: "O Messenger of Allah, will al-Rubayyi''s tooth be broken?" The Messenger of Allah (peace and blessings be upon him) said: "O Anas, the ruling of the Book of Allah is retaliation." Then the people forgave. At this the Messenger of Allah (peace and blessings be upon him) said: "Among the servants of Allah are some who, if they swear an oath by Allah, Allah fulfils it, and among them is Anas bin al-Nadr."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21034