Must I feed the poor as expiation for a vow, or may I fast, considering my age (23 years), my unfamiliarity with the needy or the amount of food to be given, and the fact that I am an orphan whose guardian I cannot rely on for help with the feeding?

Whoever makes a vow of obedience is obligated to fulfill it. Expiation is not sufficient except in the case of permanent inability to fulfill the vow, at which point an expiation for an oath (kaffarat yamin) becomes obligatory. The expiation for an oath is to feed ten poor persons, or to clothe them, or to free a slave. If one cannot find any of these, then one must fast for three days.