Should the heirs perform the Hajj al-Badal when he has not enough savings?
If a person has not performed Hajj during his lifetime when he is able to do so, then it is obligatory for his heirs to perform Hajj on his behalf using his wealth. If he has not done the pilgrimage because he cannot afford it, then it is a sunnah for his heirs to perform Hajj for him either by using the deceased/s estate, or from the property of the heir himself.
If deceased left with no estate or insufficient savings, then his heir may withdraw from his own money to perform the hajj al-badal. It is not a sin if the beneficiary does not want to use his money, as the obligatory of hajj is due to the deceased (if he is able to do it during his lifetime), and not upon his heirs. In the Qur'an, Allah says:
"ولاتزر وازرة وزر أخرى"
Meaning: "And a sinner does not bear the sins of others" (Isra ': 15)