السلام عليكم ورحمة الله وبركاته I've heard that tipping is haram. So if someone wants to tip me, do I have to reject? And if they insist on tipping and won't take the money back (possibly after I've already taken it), do I donate it to charity?

Ustadh AbdulAziz al-Haqqan

Actually, in yesterday's lesson (the first lesson on issues regarding Riba), we tackled this. You can watch it for more details.