"Only this once"

1. Ex. 10: 17
   17 Now therefore forgive, I pray thee, my sin only this once, and intreat the Lord your God, that he may take away from me this death only.
2. Judg. 16: 28
   28 And Samson called unto the Lord, and said, O Lord God, remember me, I pray thee, and strengthen me, I pray thee, only this once, O God, that I may be at once avenged of the Philistines for my two eyes.
3. Jacob 5: 69
   69 And the bad shall be cast away, yea, even out of all the land of my vineyard; for behold, only this once will I prune my vineyard.