"Let go of what is past. Let go of what is not yet. Observe deeply what is happening in the present moment, but do not become attached to it."
As a Thanissaro fanboy it's quite interesting to me, because I think I've heard several Thanissaro talks where he tells the story of the Buddha telling a monk that this is one way to meditate, but he has a better way. (Would be grateful for any references to a Thanissaro talk where he tells this story, or to the sutta he's referring to. I listen to an awful lot of Thanissaro.) So I'm curious about the provenance of this sutta.