1 Corinthians 9:13

Know ye not that they that minister about sacred things eat of the things of the temple, and they that wait upon the altar have their portion with the altar?

'Know ye not' -yet another jab at their arrogance and "knowledge".

'they that minister about the sacred things' -i.e. the priests.

'eat of the things of the temple' -'get their living from the temple' (Wms) 'The priest who serves in the Temple receives his share of the offerings and lives by them.' (Barclay p. 88) This was true in the Jewish religion (Numb. 1 Corinthians 18:8-20; Nehemiah 12:44 ff; Nehemiah 13:10), as well as in the pagan religions. Both Jew and Gentile conceded this point.