Since the land could not support both Lot's and Abraham's family, they each went their own way. Even though good land was not plentiful, Abraham allowed Lot to choose the better land because he trusted in God to fulfill his promises. (See: [[rc://en/tw/dict/bible/kt/trust]] and [[rc://en/tw/dict/bible/kt/fulfill]] and [[rc://en/tw/dict/bible/kt/promise]])
God made a covenant with Abram. This covenant was not conditioned upon anything that Abraham needed to do, but the fulfillment of its promises is conditioned upon the actions of each generation of his descendants. It has not yet been fulfilled in its entirety. This chapter continues the covenant which began in the previous chapter. (See: [[rc://en/tw/dict/bible/kt/covenant]])
Abram would have built an altar in order to offer sacrifices to Yahweh. There is an implicit understanding that building an altar was an act of worship. (See: [[rc://en/ta/man/jit/figs-explicit]])