Rashi on Genesis 37:11/רש"י על בראשית ל״ז:י״א

1שמר את הדבר OBSERVED THE MATTER — He awaited and looked forward to the time when this would come to pass. In the same sense we have (Isaiah 26:2) “that watch (שומר) for faithfulness” (i.e., for the performance of a promise) and (Job 14:16) — “לא תשמור for my sin” — which means “thou dost not wait for my sin”.