Abraham separated seven ewe lambs from the flock,

Genesis 21:27
So Abraham brought sheep and cattle and gave them to Abimelech, and the two men made a covenant.

Genesis 21:29
and Abimelech asked him, "Why have you set apart these seven ewe lambs?"

Genesis 21:30
He replied, "You are to accept the seven ewe lambs from my hand as my witness that I dug this well."

And Abraham set seven ewe lambs of the flock by themselves.