And the LORD came down in a cloud, and spake unto him, and took of the spirit that was upon him, and gave it unto the seventy elders: and it came to pass, that, when the spirit rested upon them, they prophesied, and did not cease. The Lord came down in a cloud, х be`aanaan (H6051)] - in the cloud. The purpose of this visible descent was in order to speak to Moses and the seventy elders in the presence of the people.
They prophesied, and did not cease, х wayitnab'uw (H5012)] - they spoke under divine influence. It was originally applied to those who were recipients of divine revelations or the subjects of divine inspiration (cf. Genesis 20:7; Exodus 7:1; Exodus 15:20; 1 Samuel 10:5; 1 Samuel 10:10-15; Psalms 105:15; Luke 1:68-79), but did not predict the future. Since those elders were constituted civil governors, their "prophesying" must be understood as meaning the performance of their civil and sacred duties by the help of those extraordinary endowments they had received, and by their not "ceasing," either that they continued to exercise their gifts uninterruptedly the first day (see 1 Samuel 19:24), or that these were permanent gifts, which qualitied them in an eminent degree for discharging the duty of public magistrates.