Trust in Jehovah with all your heart, and do not lean on your own prudence.
Proverbs 3: 5 King James Version (RVR1960)

The only person who always fulfills what he promises is God, this proverbs teaches us that we must trust only God since he is always for each one of us and does not fail us. Still, there are people who trust other people and forget that God curses men who trust other men.
This verse also reminds us that we must not rely on our own prudence, if we want to be prudent, we must trust God.
God teaches us to trust him, rather than ourselves since it is better to trust blindly in him, than in ourselves, just as when the father throws the baby up (something not so prudent), and he laughs because he knows for him to stop him, that is to blindly trust and God wants that in us.