Scripture is filled with instances of answered prayer.
Right off, I am reminded that God provided His law for the Israelites as an answer for them providing the way for righteousness to be reckoned before the advent of the Messiah. I recall that Abraham's desire to become all that God intended him to become required an heir, and he and Sarai were barren. David, the king of Judah, was a man of prayer and according to the Psalms that are credited to him, God answered. Elijah the prophet withheld rain for three years at his word, and then at his prayer, the heavens opened and the rain came. He gives to the beast its food, And to the young ravens that cry.