´It was narrated that Ibn 'Abbas said:` "Sa'd bin 'Ubadah Al-Ansari consulted the Messenger of Allah about an (outstanding) vow that his mother had to fulfill, but she died before doing so. The Messenger of Allah said: 'Fulfill it on her behalf.'"
Hadith ReferenceSunan an-Nasa'i / The Book of Wills / Hadith: 3692