The Testimony of the Lord Jesus
We have the testimony of the Lord Jesus Himself in John 14:1-4. In telling the Disciples of His upcoming death He gave them the promise that He would come back for them.
The Testimony of the Holy Angels
At the Ascension we have the comforting words of the holy angels. In Acts 1:11 they give the Eleven these great and comforting words: “why do you gaze up into the sky? This SAME Jesus who you see go up into Heaven will return in like manner.” This passage, along with the one in John and others in the New Testament tell us that Jesus will keep His word and come back for us personally.