What is the meaning of verses 143 and 144 from Surah Al-An'am?

In pre-Islamic times (Jahiliyyah), the polytheists would prohibit things based on their whims, so they would abandon some livestock, neither eating them nor using them. They also forbade certain fetuses of livestock and their benefits to women, as stated in the verse: "{And they say, 'What is in the bellies of these livestock is exclusively for our males and forbidden to our wives'}" [Al-An'am: 139]. So Allah clarified their falsehood. And what is meant by "{eight pairs}" [Al-An'am: 143] are eight types: the male camel, the female camel, the bull, the cow, the ram, the ewe, the male goat, and the female goat. Ibn Abbas said: "I have not forbidden anything of that, for all of it is lawful." And Allah's saying: "{Or were you witnesses when Allah enjoined you with this?}" [Al-An'am: 144] is a mockery of them. And none is more unjust than one who invents a lie against Allah to mislead people. This verse was revealed concerning Malik ibn Awf and his companions, so Allah alerted His Prophet and the believers to what He had made lawful for them, lest they become like those who forbade what Allah had made lawful.