Numbers — Chapter 28

Command the children of Israel and say to them: My oblation, my bread for my burnt-offerings of most sweet savour, you shall offer to me in their season. The daily perpetual sacrifice (tamid) must never be omitted — the pattern of the liturgical hours.

A double burnt-offering on the Sabbath, over and above the daily offering; the Sabbath liturgy is distinguished by additional sacrifices — greater holiness requires greater external worship.