大乘起信論義記 1.91

1.91

二者與下第五修行止觀門為因緣。以彼文中，雙明止觀遣凡小二執，故云治心過也。下自廣說。此當中品也。

The second serves as the condition for the below fifth gate on cultivating śamatha and vipaśyanā. In that text, śamatha and vipaśyanā are jointly elucidated to dispel the attachments of ordinary beings and the Hinayāna; hence it says "remedy mental faults." Below, this will be broadly explained of itself. This corresponds to the middling grade.