Motsa (H4161) derives from yatsa (to go out) and covers a range of 'going out' meanings: the exit of a place, the source of a spring, the east (direction of sunrise), and most powerfully, what proceeds from the mouth — God's word. 'Man does not live by bread alone but by every utterance [motsa] that proceeds from the mouth of God' (Deuteronomy 8:3).
When Deuteronomy 8:3 uses motsa for God's word, it is the living breath that sustains creation. Jesus quotes this against Satan (Matthew 4:4), insisting that life flows from every word that exits God's mouth. Water springs (motsa) that sustain physical life are analogies for the word of God that sustains spiritual life.