“Do not tarry, do not stop, no matter what happens.”

1960s, I've Been to the Mountaintop (1968)
Context: I remember when Mrs. King and I were first in Jerusalem. We rented a car and drove from Jerusalem down to Jericho. And as soon as we got on that road, I said to my wife, "I can see why Jesus used this as a setting for his parable." It's a winding, meandering road. It's really conducive for ambushing. You start out in Jerusalem, which is about 1200 miles, or rather 1200 feet above sea level. And by the time you get down to Jericho, fifteen or twenty minutes later, you're about 2200 feet below sea level. That's a dangerous road. In the day of Jesus it came to be known as the "Bloody Pass." And you know, it's possible that the priest and the Levite looked over that man on the ground and wondered if the robbers were still around. Or it's possible that they felt that the man on the ground was merely faking. And he was acting like he had been robbed and hurt, in order to seize them over there, lure them there for quick and easy seizure. And so the first question that the Levite asked was, "If I stop to help this man, what will happen to me?" But then the Good Samaritan came by. And he reversed the question: "If I do not stop to help this man, what will happen to him?".

Breathe
Breathe (2006)

The Sayings of the Wise (1555)

Source: It's Not Summer Without You

Source: Away

Source: 1984

Tim Minear, in Epiphany", episode 16 of season 2 of Angel; also mentioned in the DVD commentary for the Firefly episode, "Objects in Space".
Misattributed