It was narrated that Ibn Abbas said: A woman came to the Prophet P.B.U.H and said: '0 Messenger of Allah, my sister has died and she owed a fast of two consecutive months.' He said: 'Do you not think that if your sister owed a debt, you would pay it off for her?' She said: 'Of course.' He said: 'The right of Allah is
greater.''' (Sahih)