What is the ruling of gifting 2 nafila prayers to the ahlul bayt (A.S), what should be the intention?

Secondly, what if I cannot continue this act in near future, will I be punished for it?

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Make the intention when starting the nafl salat to gift the reward of that salat to whichever of the masumeen (as) you want.

This is a mustahab act and no punishment if you do not do it, unless you made a oath or vow by Allahs name to do it then abandoned it