大毘盧遮那成佛經疏 4.44

4.44

偈云「若弟子信心」者，謂阿闍梨觀彼現在根性或久遠因緣，於此不思議緣起三種祕密諸方便中，直信不疑無有能怖畏，乃堪攝受。餘如師德中說。

The verse says: 'If a disciple has faithful mind', which means that the ācārya contemplates the disciple's present capacity or long-standing conditions, and if in the face of these inconceivable conditioned arisings and various upāyas of the three mysteries, he has straightforward faith without doubt and has nothing to fear, only then is he fit to be adopted. The rest is as explained in the master's virtues.