Exodus 24:18

Moses went into the midst of the cloud It was an extraordinary presence of mind which the grace of God furnished him with, else he durst not have ventured into the cloud, especially when it broke out in devouring fire. And Moses was in the mount forty days and forty nights It should seem the six days were not part of the forty; for during those six days Joshua was with Moses, who did eat of the manna, and drink of the brook mentioned Deuteronomy 9:21, and while they were together, it is probable Moses did eat and drink with him; but when Moses was called into the midst of the cloud, he left Joshua without, who continued to eat and drink daily while he waited for Moses' return, but from thenceforward Moses fasted.