Abraham said to his young men, “Stay here with the donkey, and I and the lad will go over there; and we will worship and return to you.” –Gen. 22:5
The first sacrificial offering recorded in Scripture occurs in the story of Cain and Abel in Genesis chapter 4. Among other things, through that story we learn that ritual offerings to God are at least in their nascent stage of development even as early as Adam and Eve's first generation of children. Then, the idea of bringing an offering to God develops over time into a highly regulated, fully-blown legislative and ceremonial Israelite practice—as exemplified by the laws given to Moses on Mt. Sinai (see Lev. 1-7). However, in the time of Abraham, the offering (whether animal or other) was basically meant as a gift to God.
So, when Abraham says to his servants, "You guys stay here while Isaac and I worship over there," he's equating worship with the burnt offering he's about to make. In Abraham's mind, the essence of worship is an offering to God. Scripture makes this connection elsewhere, too. For example, the psalmist says, "Ascribe to the LORD the glory of His name; Bring an offering and come into His courts. Worship the LORD in the splendor of holiness..." (96:8-9). But, since we no longer offer animals to God as worship, Hebrews says to offer a sacrifice of praise (13:15). Further, Paul says to offer our bodies (and lives) as our spiritual worship—as opposed to physical animal-sacrifice (Rom. 12:1-2). Peter puts it this way, "...you also...are being built up as a spiritual house for a holy priesthood, to offer up spiritual sacrifices acceptable to God through Jesus Christ"—i.e., everything we do should be a worship offering to God!