Musannaf Ibn Abi Shaybah 16754 — Two guardians who both give

Thabit bin Qays al-Ghifari said: I wrote to Umar bin Abd al-Aziz that a girl of the tribe of Juhaynah was married off by her guardian to a man of the tribe of Qays, while her brother married her off to a man of Juhaynah; whose wife will she now be? Umar bin Abd al-Aziz said: Bring upright witnesses before her, then give her the choice; whichever of them she chooses is her husband.