Sponsorship letter from Visitor's Parent

[questions999]

Hello!
I am living in the UK and am hoping my partner can get a visitor visa to visit me for a few weeks.
We are writing the sponsorship letter for him from his father, as he will be financing the trip.

I've tried searching some example letters but they seem to all be from the UK sponsors, in this situation his foreign father is the sponsor. Does anyone know what information is required in the letter? Do we need to talk about how long he's staying, where, why, and prove he will return to his country? Or is it as simple as his father saying he will finance the trip?
Thank you

[zimba]

I do not understand why many people repeat this but there is no such a thing as sponsorship under the UK immigration rules for standard visit visa. Your partner is expected to satisfy the visa officers on his own when applying for a visit visa. He should submit documents showing he has enough money (support letter from his dad, evidences of finances, etc) and have something going on at home country to prove he will go back at the end of his visit. UKVI often does not allow such visits as some visitors do not leave the UK, particularly if they come from non-EU countries with high emigration rate