Unto his ordre he was a noble post.
(= of his order, he was a noble supporter.)
‘Post’ means, here, almost literally, someone who supported the church.
This couplet, which rhymes the ‘cost’ of finding husbands for women he’s seduced with the ‘post’ of supporting the Church, amounts to a fairly brutal attack on the Friar as a man, but more importantly, to Friars in general. With the click of a rhyme, Chaucer marries (forgive the pun) the Church with illicit sex.
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