大乘起信論廣釋卷第三．四．五 5.100

5.100

論。十者至之所驚動　釋曰。若得三昧者。非謂創得也。意說。若時得住三昧。心如虛空無罣礙。故唯有廣聲終無驚動。故新本云。若住於定。

[Treatise:] Tenth, [if they attain samādhi, they cannot be] alarmed or shaken [by any external sounds].
[Commentary:] "If they attain samādhi" does not mean newly attaining it. The intention is to say that when they can abide in samādhi, the mind is like empty space, without obstruction; therefore, even if there are loud sounds, they are never alarmed or shaken. Thus the new text says: "If they abide in concentration."