1 Sam 20:5

20:5 the new moon. This festival was a time of rejoicing at the beginning of each month. It was marked by the sounding of trumpets (Num. 10:10; Ps. 81:3) and special sacrifices (Num. 28:11–15). The festival is often mentioned in conjunction with the Sabbath (2 Kin. 4:23; 1 Chr. 23:31; Neh. 10:33; Is. 66:23; Ezek. 46:3) and may have been subject to similar regulations (Amos 8:5). The new moon celebration is mentioned once in the New Testament (Col. 2:16).