Мидраш к Дварим 1:33

(Bamidbar 10:34) "And the cloud of the L-rd was above them by day": From here they said: There are seven "clouds": (Bamidbar 14:14) "and in a pillar of cloud You go before them by day," (Shemot 14:19) "and the pillar of cloud turned from before them," (Bamidbar, 14:14) "and Your cloud stands over them," (Devarim 1:33) "and in cloud by day," (Bamidbar 9:19) "And when the cloud lingered over the mishkan," (Shemot 40:38) "For the cloud of the L-rd was on the mishkan by day," (Bamidbar 10:34) "And the cloud of the L-rd was above them by day." There were seven clouds — four on their four sides, one above, one below (to cushion their feet), and one before them, which lowered what was high and raised what was low, and killed the serpents and the scorpions, and swept and sprinkled before them. R. Yehudah says: There were thirteen (clouds) — two on each side, two above and two below, and one before them. R. Yoshiyah says: Four. Rebbi says: Two.