44 The verb is a preterite with vav (ו) consecutive; here, the second clause, is subordinated to the first preterite, because it seems that the entering into the cloud is the dominant point in this section of the chapter.
45 B. Jacob (Exodus, 750) offers this description of some of the mystery involved in Moses’ ascending into the cloud: Moses ascended into the presence of God, but remained on earth. He did not rise to heaven—the ground remained firmly under his feet. But he clearly was brought into God’s presence; he was like a heavenly servant before God’s throne, like the angels, and he consumed neither bread nor water. The purpose of his being there was to become familiar with all God’s demands and purposes. He would receive the tablets of stone and all the instructions for the tabernacle that was to be built (beginning in chap. 25). He would not descend until the sin of the golden calf.

In other versions

Moses entered the cloud and went up on the mountain. And Moses was on the mountain forty days and forty nights.

Then Moses entered the cloud as he went on up the mountain. And he stayed on the mountain forty days and forty nights.

Moses entered the cloud as he went up the mountain, and he remained on the mountain forty days and forty nights.

Then Moses disappeared into the cloud as he climbed higher up the mountain. He remained on the mountain forty days and forty nights.

And Moses went into the midst of the cloud, and he went up the mountain, and Moses was on the mountain forty days and forty nights.

And Moses went into the midst of the cloud, and gat him up into the mount: and Moses was in the mount forty days and forty nights.

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