In the third month, when the children of Israel were gone forth out of the land of Egypt, the same day came they into the wilderness of Sinai.
In the third month - according to Jewish usage, the first of that month - "same day," it is added, to mark the time more explicitly - i:e., 45 days after leaving Egypt-one day spent on the mount (Exodus 19:3), one returning people's answers (Exodus 19:7-8), three days of preparation-making the whole time fifty days from the first Passover to the promulgation of the law. Hence, the Feast of Pentecost, i:e., the 50th day, was the inauguration of the Old Testament Church; and the divine wisdom is apparent in the selection of the same season for the restitution of the New Testament Church (John 1:17; Acts 2:1).
Wilderness of Sinai. This name is here used for the first time. Thenceforth, with one exception (Exodus 33:6), during the whole sojourn of the Israelites in the vicinity, Sinai alone is spoken of (Exodus 7:18; Exodus 7:23; Exodus 24:16; Exodus 31:18; Exodus 34:29; Exodus 34:32; Leviticus 7:38; Leviticus 25:1; Leviticus 26:46; Leviticus 27:34; Numbers 1:1; Numbers 3:11; Numbers 3:14). In Numbers 10:12 they break up from Sinai; and in the list of stations (Numbers 33:15), Sinai also naturally appears. But elsewhere, after their departure, and through the whole book of Deuteronomy (except in the Song of Moses, Deuteronomy 32:2), Horeb alone is named; and the same events are spoken of as occurring in Horeb which were before described as taking place on Sinai (Deuteronomy 1:2, Deuteronomy 1:6, Deuteronomy 1:19; Deuteronomy 4:10, Deuteronomy 4:15; Deuteronomy 5:2; Deuteronomy 9:8; Deuteronomy 18:16; 28:69). Horeb and Sinai seem to be used in some cases indifferently as the designation of the mountain of the law. But in general Horeb is the name of the mountainous region, and Sinai is the specific one of the central district (Robinson, 'Biblical Researches,' vol. 1:, p. 551; Hengstenberg, 'Pentateuch,' vol. 2:, p. 396).