Sforno on Exodus 19:2/ספורנו על שמות י״ט:ב׳

1ויסעו מרפידים ויבאו מדבר סיני. The departure from Refidim was for the express purpose of getting to the desert of Sinai where the mountain of G’d (Chorev) was located. The people knew that once they would arrive there they would worship the Lord there (Exodus 3,12).