14 years ago my 20 years old cousin was killed in a car crash. On the Saturday before his death I went up to his house and he wasn't in, I spoke to my auntie and uncle and said that I'd come and pick him up Sunday evening and we'd do something and he could stay at mine. I never did what I said I would and on the Monday morning whilst being driven to work by some fucking shitbag he was involved in a car crash that killed him.
The morning of his death we went around to his parents house and the second I walked through the door his dad said "you never did come and pick him up"
I still think about that phrase on a daily basis. I don't think it was ill-intentioned, but it fucking stung like nothing else