Rule with a rod of iron/with an iron hand phrase
To control a group of people in a very strict way
He is a very tough boss. He has ruled us with an iron hand.
The verb "rule" must be conjugated according to its tense.
This term comes from Tyndall’s translation of the Bible (1526): “And he shall rule them with a rodde of yron.” It was later transferred to any kind of stern domination, either serious or ironic.
A humorous way of saying that what one has said is just what they acknowledge and may not be entirely accurate
Mike: Have you returned from your vacation on the beach? Your skin seems to get tanned.
Jenny: My skin is always dark. That's my story and I'm sticking to it!