One In-Hand Is Worth Two In-Bush
One day a fisherman went for fishing to a river as usual. He casted his net into the river and sat waiting for the fish to get into it.
After some time, he drew up the net and saw a tiny fish in it. He took the fish out and put it into his basket.
He was about to cast his net again into the river when the tiny fish begged him, "Sir, please put me back into the river otherwise I shall die.
I am very small and of little use for you and if you put me back in water then, after a few days, I shall grow big and then, you can catch me again and I shall be more useful to you then."
The fisherman said, "Oh no! Once I have caught you, how can I let you go like this because later I may never catch you again. I am not that foolish."
So, the fisherman was wise enough and didn't give up the certain for something uncertain.