'Theirs' in the Bible

Why harden your hearts as the Egyptians and Pharaoh hardened theirs? When He afflicted them, didn’t they send Israel away, and Israel left?

I hear that you are shearing. When your shepherds were with us, we did not harass them, and nothing of theirs was missing the whole time they were in Carmel.

Nothing of theirs was missing from the youngest to the oldest, including the sons and daughters, of all the plunder the Amalekites had taken. David got everything back.