Numbers 29:12-13

12And on the fifteenth day of the seventh month ye shall have a holy convocation: no manner of servile work shall ye do; and ye shall celebrate a feast to Jehovah seven days;

13and ye shall present a burnt-offering, an offering by fire for a sweet odour to Jehovah: thirteen young bullocks, two rams, fourteen yearling lambs (they shall be without blemish);