Exodus 13:17 "In six days the Lord made heaven and earth, and on the seventh day he rested, and was refreshed."
Isaiah 40:28 "The everlasting God, the LORD, the Creator of the ends of the earth, fainteth not, neither is weary. "
These two scriptures only appear contradictory when read and understood in light of our modern and Western way of thinking. The problem is not necessarily one of translation, but rather one of understanding the Hebrew idiom involved.
In Genesis 2:2 we also read: "And on the seventh day God ended his work which he had made; and he rested on the seventh day from all his work which he had made." From this we can see that the "resting" is simply an expression stating that God's "work" was completed, was finished. There is no indication that He had gotten tired or worne out by His work, rather the emphasis is clearly put on the fact that the work was finished. The use of "rested", as well as the later expression in Exo 31:17 of "and was refreshed" are part of an oriental idiomatic way of saying that God "sat back and surveyed what He had completed". Isaiah 40:28 states the literal truth regarding God's endurance and power, that he won't ever get exhausted or tired in or from His doings! When understood as part of an oriental idiom, the expression "rested and was refreshed" is not in any way contradictory to Isaiah's statement, but rather emphatically shows God's delight in His accomplished work, expressed especially by the word "rested [sat down]".
Thus, there is definitely no contradiction between these passages, except it be within our own understanding of each of these verses.