This is a bit hard to explain but here's an example:

I wanted to spend Christmas with him, but he said he had __ with his family in Ireland this year.

What to fill in the blank?

Initially, I wrote to do it but a native English speaker said it wasn't quite correct.

This is a bit hard to explain but here's an example:

I wanted to spend Christmas with him, but he said he had __ with his family in Ireland this year.

What to fill in the blank (a phrase that doesn't include spend)?

Initially, I wrote to do it but a native English speaker said it wasn't quite correct.