Is it permissible to vow to pray two voluntary rak'ahs after every obligatory prayer performed at home instead of in the mosque?

Whoever vows to pray two rak'ahs after missing a congregational prayer must perform them during the time when supererogatory prayers are permissible. Thus, he should avoid praying after Fajr until the sun has risen, and after 'Asr until it has set, in accordance with the Prophet's (peace be upon him) saying: "Whoever vows to obey Allah, let him obey Him."