Verses 36-38 list various trials God has required of some of the faithful. Especially notice verse 39: "And all these, having obtained a good testimony through faith, did not receive the promise." Even though all looked lost from a human standpoint, they still believed God, knowing that the sovereign God could and would keep His promises even beyond the grave.
With all of God's promises, He does not promise when He will answer. The timing of those answers is in His hands. Based on what is best, God, who is love (I John 4:8,16), decides when (Ecclesiastes 3:11). The right time may be, not in this life, but in the next. In fact, believing God's promises, even to the end—death—could be the last piece of proof God requires to "know" He can entrust us with eternal life, an everlasting relationship with Him.
Faith—What Is It?
Other Forerunner Commentary entries containing Hebrews 11:38: