سنن النسائي

Muhammad bin 'Abdullah bin Yazid said: "Sufyan narrated to us from Az-Zuhri, from 'Ubaidullah bin 'Abdullah, from Ibn 'Abbas, that Sa'd said: 'My mother died and there was an (outstanding) vow that she had to fulfill. I asked the Prophet (ﷺ) and he told me to fulfill it on her behalf.'"