Psalm 17:15
New International Version
15 As for me, I will be vindicated and will see your face;
when I awake, I will be satisfied with seeing your likeness.
David believed in life after death. Belief in resurrection in Old Testament time was not as wide spread. It was partially understood. They knew they would not be abandoned. Thanks to Jesus, we have a better understanding. We know that we have eternal life with Jesus as a believer.
