A man vowed to slaughter an animal for the sake of Allah Almighty. After some time, he wanted to sell it and replace it with another one because of his financial inability. Is this permissible?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

The Muslim should fulfill his vow in the way that he vowed. It is impermissible for him to replace it with another. The texts of the Quran and the Sunnah enjoined fulfilling vows.

Allaah Almighty says (what means): {Then let them end their untidiness and fulfill their vows.} [Quran 22: 29]

The Prophet, sallallaahu ‘alayhi wa sallam, said: “If one vows to obey Allaah Almighty, he should obey Him. If one vows to disobey Allaah Almighty, he should not disobey Him.” [Al-Bukhari and others]

For this reason, it is impermissible for this man to sell the sacrificial animal that he specified for the vow and substitute it with another.

Allaah Knows best.