Abdullah bin Abbas reported,

A woman came to the Prophet ﷺ and said, "My mother vowed to perform the pilgrimage, but she died before she could do so. Should I perform the pilgrimage on her behalf?"He replied, "Yes, perform the pilgrimage on her behalf. Tell me, if your mother had a debt, would you not pay it off?"She said, "Yes."He said, "Then fulfill what is owed to Allah, for Allah is most deserving of being repaid."

Azami 7128

Sahih

عن ابن عباس

أن امرأة جاءت إلى النبي ﷺ فقالت: إن أمي نذرت أن تحج، فماتت قبل أن تحج أفأحج عنها؟ قال: نعم حجي عنها، أرأيت لو كان على أمك دين أكنت قاضيته؟ قالت: نعم، قال: فاقضوا الله الذي له، فإن الله أحق بالوفاء.

الأعظمي 7128صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Oaths and vows
Chapter
Vows
Section
Fulfilling a vow of Hajj on behalf of the deceased
Numbering
Jami al-Kamil 7128 (2nd edition)
Azami 7128