Which brother urged throwing Joseph into a pit, planning to rescue him later?

Answer: Reuben

"Do not shed his blood. Throw him into this pit," said Reuben, intending to rescue Joseph and return him to his father.

“When Reuben heard this, he tried to rescue Joseph from their hands. “Let us not take his life,” he said. “Do not shed his blood. Throw him into this pit in the wilderness, but do not lay a hand on him.” Reuben said this so that he could rescue Joseph from their hands and return him to his father.”— Genesis 37:21-22 (BSB)