Khabib posted a caption along with the friendly photo which says, "Thank you for the hospitality of [Ramzan Kadyrov]. May the Almighty protect you and the entire Chechen people."

The issue ... just last month, multiple media outlets, including the BBC, reported that Chechen officials rounded up gay people and tortured them. At least 2 people died, according to the reports.

For his part, Kadyrov has denied the "gay purge" as "complete lies" -- mostly because he does not believe there are any gay people in Chechnya.

Seriously. He has said it multiple times on the record.

In fact, when asked specifically about the "gay purge," Kadyrov told a reporter -- "all those who defend human rights groups and the gays we supposedly have in the Chechen Republic are foreign agents. They've sold out their country, their people, their religion, everything."

Khabib isn't the first huge star to pose with Ramzan, who happens to be a huge combat sports fan -- he's also hung out with Floyd Mayweather.