I had to double check.

He never pledged to run for one term, he made several statements that he was a bridge to the next generation of leadership he did not expect to run for a second term but he never explicitly ruled it out.

I would post a link but I'm not a lib, you know how to Google, and the best article looks like it's from the Atlantic which I refuse to give free clicks to.

But TLDR, yes he made very clear he planned to run for exactly one term. No, he did not promise or pledge to run for one term.