Adam Clarke on 1 Chronicles 23:29

Both for the shew-bread - It was the priests' office to place this bread before the Lord, and it was their privilege to feed on the old loaves when they were replaced by the new. Some of the rabbins think that the priests sowed, reaped, ground, kneaded, and baked the grain of which the shew-bread was made. This appears to be a conceit. Jerome, in his comment on Mal 1:6, mentions it in these words: "Panes propositionis quos, juxta traditiones Hebraicas, ipsi serere, ipsi demetere, ipsi molere, ipsi coquere debebatis."

For all manner of measure and size - The standards of all weights and measures were kept at the sanctuary, and by those there deposited all the weights and measures of the land were to be tried. See the note on Exo 30:13.