In the fourteenth day of this month, at even, ye shall keep it in his appointed season: according to all the rites of it, and according to all the ceremonies thereof, shall ye keep it. (Numbers 9:3)
Literally, “between the evenings.” The precise meaning of this phrase is difficult to determine (see on Ex. 12:6).The same expression is found also in (Ex. 16:12; 29:39, 41; 30:8; Num. 28:4).