大乘起信論義記 2.23

2.23

答中言不相離者，以體相不相離故。如金與莊嚴具，若以金收具，具無所遺；以具攝金，金無不盡。良以二門一揆，全體遍收。此義亦然，思之可見。

In the answer, "not separate from each other" means that essence and marks are not separate from each other. Like gold and ornaments: if one gathers the ornaments with the gold, no ornament is omitted; if one subsumes the gold with the ornaments, the gold is entirely included. Truly, because the two gates share a single trajectory, the entire essence is completely gathered. This meaning is also like this; by contemplating it, it can be seen.