Matthew Poole and continuators on Numbers 28:23

23 Ye shall offer these beside the burnt-offering in the morning , which is for a continual burntoffering.

And that in the evening too, as is evident from the nature of the thing and from other scriptures, but the morning-sacrifice alone is mentioned, partly because the celebration of the feast began with it, and principally because this alone was doutbful, whether this might not be omitted when so many other sacrifices were offered in that morning, whereas there was no question but the evening sacrifice should be offered, when there were none other besides it to be offered.