The Shabbat Additional Offering (Musaf)
Requires Beit HaMikdash
BaMidbar 28:9 On the Shabbat day [the offering shall be] two yearling lambs without blemish, and two tenths [of an efah] of fine flour as a mincha-offering, mixed with [olive] oil, and its libation.
We are commanded to offer a sacrifice on every Shabbat in addition to the daily olah-offering. The order of the service on the Shabbat was as follows, the daily olah-offering of the morning was brought at sunrise; then the two dishes of frankincense that lay on the Table of Showbread were burnt; the Kohanim then ate the twelve loaves of the Showbread (P27); the Musaf-offering followed, and the services closed with the daily olah-offering of the evening.
Since the Kohanim changed Courses on the Shabbat, a special prayer was offered by the outgoing Courses on behalf of the incoming one: 'May He who has caused His Name to dwell in this House, likewise cause love, brotherhood, peace and fellowship to dwell in your midst' (Ber.12a).
It should be noted that while at the daily olah-offerings the Leviim chanted certain Tehillim, at the Musaf-offering of the Shabbat they changed parts of the Song of Moshe (Devarim 32:1-52; Rosh Hashanah 31a)