Exodus 33:4-6
4 And when the people heard this bad word, they mourned, and no one put on his headgear.
5 For YHWH said to Mosheh, Say to the sons of Yisrael, You are a stiff-necked people: in the blink of an eye I will come up into your midst and consume you! And now, put off your headgear from upon you: and I will make known to you what I will do with you.
6 And the sons of Yisrael plucked off their headgear from mount Ḥoreb.
Sinai and Horeb are not the same. Horeb is the mount of Elohim and is of above, (the mind, your heavens, the throne of the Most High). Sinai is of below, (the heart, the soil, the flesh, the earth).
So then, with the mind (Horeb, of above) I myself serve the Torah of Elohim: but with the flesh (Sinai, of below) I serve the Torah of the sin-offering, (mortify the deeds of the body, Rom 8:13, mortify your members upon-concerning the earth, (of below), Col 3:5).