It seems that this was merely a precautionary
measure adopted by the Prophet (sws) lest people should start giving preference
to his family in case they had to choose between a person who deserved charity
from among his own family and someone else.
Perhaps the Prophet (sws) also had before him the evil
that had crept into the family of the Prophet Moses (sws). Moses’ family/tribe
was called the Levites. It had been divinely ordained that the Levites would
receive the tithe (1/10 th share of the harvest).
This had made them corrupt. The Prophet (sws) thinking that the same fate might
befall his family, forbade Sadqah for them.
This of course was a directive of those times. It has no
link with the survivors of the Prophet’s family found today.