God revealed Himself to Moses from the midst of a small thorn bush, which burned with fire but was not consumed. The Sages explain the significance of the revelation’s coming specifically from the midst of thorns.

Just as with regard to twins, if one’s head aches the other feels it, so too, the Holy One, blessed be He, said, as it were: “I am with [the children of Israel] in [their] distress” (Psalms 91:15)…. The Holy One, blessed be He, said to Moses: Don’t you feel that I am in distress just as Israel is in distress? Know it from the place that I am speaking to you, from the thorns. As it were, I share their distress. (Shemot Rabba 2)