Rashi on Exodus 24:1/רש"י על שמות כ״ד:א׳

1ואל משה אמר AND UNTO MOSES HE SAID — This section was spoken before the Ten Commandments were given (i. e. אמר is the pluperfect); it was the fourth of Sivan when “Come up” was said to him (Shabbat 88a).