Is expiation (kaffarah) obligatory for one who vowed not to speak to his maternal uncle and not to enter his house, then regretted it?

Vows are of two types: what is for Allah, its expiation is fulfilling it; and what is for Satan, there is no fulfillment in it, and it requires an expiation for a broken oath (kaffarat yamin).

So, if the vow is an act of obedience to Allah, it is obligatory to fulfill it. If it is an act of disobedience, it is impermissible to fulfill it, and it requires an expiation for a broken oath.

If it is disliked (makruh) or permissible (mubah), then it requires an expiation for a broken oath, according to the saying, "The expiation for a vow is the expiation for an oath." This is the madhhab of Imam Ahmad, Ishaq, and the Hanafis.