Prior to the giving of the Law (for our purposes we will use the book of Genesis only), the word worship is used four times in Genesis: Genesis 22:5; 24:26; 24:48; and 47:31. The worshipers in these passages are Abraham, Isaac, Abraham’s servant, and Israel. While Abraham and Isaac worshiped together, his servant and Israel worshiped alone. Abraham and Isaac’s worship was planned, to an extent, for he said, “I and the lad will go over there; and we will worship and return to you.” The servant and Israel’s worship, however, was spontaneous and came from an overwhelming emotion of thankfulness. Both of these may occur in our lives, but for many years of my life, I would have only recognized the validity of the one: the planned, formulated, procedural worship. In my own life, and I am sure this is true with you, there have been times when you have been overwhelmed by the love of God and have been moved to shout for joy, sing, dance, pray, or even play a song.
To learn more about worship in Genesis, we have to use what we learn of worship in passages like Genesis 22 and apply it to other texts. For example, while the word worship is not used, Cain and Abel both offered up worship to God through sacrifice (Genesis 4). Noah, before the Law, also offered sacrifices with the added detail that there were clean and unclean animals (Genesis 7:2; 8:20).
One interesting side note that is not directly related to worship: in Genesis 15, God reiterates His promise to Abraham, and Abraham responded, “O Lord God, how may I know that I will possess it?” (Genesis 15:8). To show Abraham that God would keep His promise, He made a covenant with Abraham modeled after traditions of the day (Genesis 15:9-17). According to the JPS Torah commentary,
In response, God contracts a solemn covenant with the patriarch, who becomes the passive beneficiary of His unilateral obligation, unconditionally assumed. It would seem that the form of this covenant is modeled after the royal land-grant treaty common in the ancient Near East. By this instrument a king bestows a gift of land on an individual or vassal as a reward for loyal service.
In this scenario,
God uses common customs to communicate effectively with Abraham. God did not
have to do this; he could have summoned a whirlwind, divided a river, or caused
an earthquake to prove to Abraham that He was there. Instead, He took something
that Abraham, as a man from a wealthy family, would know and convinced Abraham
of His faithfulness. Are there other situations in Scripture where God takes
from someone’s or some people’s culture, tradition, or personal talents and makes
it part of a covenant or ritual? We’ll see tomorrow!
 Sarna, Nahum M. Genesis. Philadelphia: Jewish Publication Society, 1989. Print. The JPS Torah Commentary.