Commentaries:
Even after Jesus died, He could not wait to get back and tell them more and more about the Kingdom of God, which then He was sending them out to preach. It almost seems as if He was not quite finished telling them everything by the time He died, so He appeared to them during forty days time to give them further instruction. If we could say such of Him, He was "obsessed" with—driven by—the idea of preaching the Kingdom of God. He instilled that "obsession" in His apostles, as we see in spades in the apostle Paul.
Richard T. Ritenbaugh
Itching Ears
Other Forerunner Commentary entries containing Acts 1:3:
Malachi 3:1
Mark 1:14-15
Luke 7:10
Galatians 1:6