Contradiction with Exodus 4:10
Moses claimed he was not eloquent and slow of speech, which contrasts with God sending him to speak, as Psalms 105:26 suggests his readiness.
Exodus 4:10: And Moses said unto the LORD, O my Lord, I [am] not eloquent, neither heretofore, nor since thou hast spoken unto thy servant: but I [am] slow of speech, and of a slow tongue. [eloquent: Heb. a man of words] [heretofore: Heb. since yesterday, nor since the third day]
Contradiction with Exodus 6:12
Moses doubted his ability to speak to Pharaoh, contradicting the implication in Psalms 105:26 of his suitability as God's messenger.
Exodus 6:12: And Moses spake before the LORD, saying, Behold, the children of Israel have not hearkened unto me; how then shall Pharaoh hear me, who [am] of uncircumcised lips?
Contradiction with Numbers 12:1-2
Miriam and Aaron questioned Moses' unique leadership role, opposing the clear selection of Moses as leader in Psalms 105:26.
Numbers 12:1-2: And Miriam and Aaron spake against Moses because of the Ethiopian woman whom he had married: for he had married an Ethiopian woman. [Ethiopian: or, Cushite] [married: Heb. taken]
Contradiction with Exodus 3:11
Moses questioned his worthiness to lead the Israelites, conflicting with the decisiveness of his calling in Psalms 105:26.
Exodus 3:11: And Moses said unto God, Who [am] I, that I should go unto Pharaoh, and that I should bring forth the children of Israel out of Egypt?