The Shulchan Arukh (OC 328:14) rules that if a person is sick on Shabbat and needs meat, it is better to slaughter an animal for them than to feed them an animal that wasn’t slaughtered according to the halakha. This, despite the fact that slaughtering an animal on Shabbat is a far graver violation than consuming non-kosher meat.
There are several reasons for this, the one in the Tur being that,by a sick person, Shabbat is like a weekday. The mechaber’s reason, which he mentions in his Bet Yosef (ibid.), is that it is better to commit a one-off violation than it is to commit frequent violations, even when those frequent violations are of a lesser order. Although there were scholars before the Tur who expressed the same halakha (notably the Rosh and the Mordekhai), this particular reason for it is attributed by the Bet Yosef to Rabbeinu Nissim (“the Ran”; Yoma 4b, s.v. וגרסינן), who holds that when eating non-kosher meat one is in violation of the halakha with every olive-sized mouthful.
As the Tosafot point out, bnei Noach were also warned about murder. Why would Avraham think that they would violate a more serious prohibition in order that they might not violate the milder one? Their resolution, which is subsequently quoted by both the Rosh and the Chizkuni in their commentaries on the Torah, is that it is better to transgress a serious prohibition once than it is to transgress a mild prohibition several times.
If I am correct in supposing that the origins of this idea lie in the writings of the Tosafot, and that it was their resolution that influenced the halakha of the Ran, then we have in our Shulchan Arukh a ruling that (at least according to its author) is learnt out, not “from Sinai”, but through the postulated behaviour of Egyptians.