What are the emphasized Sunnahs of prayer?

A vow to perform a fard (obligatory) prayer is not valid, because it is a commitment to what is already obligatory. However, a vow to perform confirmed sunnah prayers is valid and binding. The criterion for these is what the Prophet, peace and blessings be upon him, consistently observed. They can be summarized into six categories, including a second type that is prayed in congregation, such as the two 'Eids, the prayer for rain (Istisqa'), and the prayers for solar and lunar eclipses.