This is an idiom. "because you always thought and desired the right things" (See: [[rc://en/ta/man/translate/figs-idiom]])
# so that he may make come true the word
Here the metonym "the word" refers to what God has promised. AT: "so that he may fulfill the promise" (See: [[rc://en/ta/man/translate/figs-metonymy]])
# your ancestors, to Abraham, Isaac, and Jacob
Abraham, Isaac, and Jacob are the "ancestors" of whom Moses is speaking.