Contradiction about Moshe

Question

It says in Shemot 17:12:

"But Moses’ hands grew heavy; so they took a stone and put it under him and he sat on it, while Aaron and Hur, one on each side, supported his hands; thus his hands remained steady until the sun set."

Yet at the end of the Torah, in Devarim 34:7 it says:

"Moses was a hundred and twenty years old when he died; his eyes were undimmed and his vigor unabated."

In one place it says that his arms grew heavy, but in another place it says that in all his 120 years, he didn't lose his vigor/strength. Don't these two contradict each other? Is there an answer?

Answer 1

The Ibn Ezra says (and others like the Chizkui also say) that no one can be expected to hold his hands up for so long without getting tired, but Rashi seems to say that the "heaviness" that Moshe felt was not a function of his personal strength and vigor, but (via Sefaria)

Because he had shown himself remiss in the duty that was his, of waging war himself against Amalek, and had appointed another in his stead, his hands became heavy (cf. (Mekhilta d'Rabbi Yishmael 17:12:1).

Others also say that the reason his hands became hard to hold was not for literal and physical reasons but spiritual ones (see the Haamek Davar).

Answer 2

Are there contradictions in the Bible?

Verse 34:7,

"Now Moses was 120 years old when he died; his eyes were not dim and his natural forces hadn't abated."

Rashi opines that there is no contradiction. Abraham ibn Ezra agrees. He posits that Moses was old, and although weak to lead the people, when he died his eyesight was still sharp, the bodily moistures had not become dry as it often does with old men. Thus, it appears that there is no contradiction here.