Sforno on Deuteronomy 9:7/ספורנו על דברים ט׳:ז׳

1זכור אל תשכח, Moses adds proof to his characterising the Jewish people as being stiff-necked by reminding them of how many times during his stewardship of the nation they had angered G’d, so that it reminds one of a dog which returns to his own excrement finding it attractive. This happened again and again although each time they had been subjected to disciplining by G’d, and they learned more about His greatness on each occasion.