Jesus told his disciples he was going to his Father's house to do what for them?

Answer: Prepare a place

Jesus said he was going to prepare a place for them, and would come back so they could be where he is.

“In My Father’s house are many rooms. If it were not so, would I have told you that I am going there to prepare a place for you? And if I go and prepare a place for you, I will come back and welcome you into My presence, so that you also may be where I am.”— John 14:2-3 (BSB)