'Right hand' in the Bible

Then he brought them both close to his father, placing Ephraim with his right hand toward Israel's left and Manasseh with his left hand toward Israel's right.

But Israel stretched out his right hand, laying it on Ephraim's head (he was the younger son) and laying his left hand on Manasseh's head (even though Manasseh was the firstborn).

But Joseph observed that his father had laid his right hand on Ephraim's head. That displeased him, so he grabbed his father's hand and started to move it from Ephraim's head to Manasseh's head.

"No, father, this one is the firstborn. Place your right hand on his head."