These are : "He was oppressed and afflicted, yet he did not open his mouth; he was led like a lamb to the slaughter, and as a sheep before its shearers is silent, so he did not open his mouth" and   "I had been like a gentle lamb led to the slaughter...", both of which were very frequently cited by medieval commentaries. In medieval typology, Isaac carrying wood up the mountain for his sacrifice is the most common parallel for the episode, and often shown as a complementary scene; this scene is "Isaac Bearing the Faggots" (or "wood") in traditional art history terminology.
In these passages, the prophet Isaiah describes himself as being subjected to persecution and hardship without speaking out, likening his situation to that of a lamb being led to slaughter. This theme is also echoed in medieval typology, where Isaac carrying wood up the mountain for his sacrifice is often depicted as a complementary scene; this scene is "Isaac Bearing the Faggots" (or "wood") in traditional art history terminology.