In Jesus' parable, who built his house on the rock?

Answer: A wise man

Jesus said everyone who hears his words and acts on them is like a wise man who built his house on the rock.

“Therefore everyone who hears these words of Mine and acts on them is like a wise man who built his house on the rock. The rain fell, the torrents raged, and the winds blew and beat against that house; yet it did not fall, because its foundation was on the rock.”— Matthew 7:24-25 (BSB)