俱舍論記 2.53

2.53

「頌曰至意諸念為體」者，答。上兩句正答。言「無分別」，無二分別。下兩句出二分別體。

Regarding "The verse says: ... are in essence mental instances of mindfulness": This is the answer. The upper two lines provide the direct answer. The statement "non-conceptual" means lacking two kinds of conceptualization. The lower two lines reveal the essence of these two conceptualizations.