Shut em off they sucker songs
Fuck em all and the horse they rode in on

from Jay Electronica (Ft. Yasiin Bey) – Exhibit B Lyrics on Rap Genius

Mos is saying shut up to the haters who try to take them down and belittle their song.

The reference to the horse is Mos saying that the haters came in on another being instead of walking in on their own two feet. This reiterates the idea of rich vs the poor in the song.

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