On www.phrases.org.uk there is reference to this phrase coming from the field of horse training. When buying a horse it is said that one puts the horse through its paces: this means that one tests the horse to see how it walks, runs, et cetera. That is what we do with people: test them to see if they have the ability to do what is needed of them.

Übersetzung:

jemanden auf Herz und Nieren prüfen

Gegenteil(e)

to leave someone to their own devices

Synonym(e):

to put someone to the test