首楞嚴義疏注經 2.620

2.620

若汝執言，掌雖生觸，須待合時此觸方出。若爾合既觸出，離應觸入。若觸入時，所經之處應亦覺知觸入蹤跡。若實覺知，觸常在體，應須常知，何待合知。

If you insist: 'Although the palms give rise to contact, it must wait until they join for this contact to come out.' If so, since when joining, contact comes out, then when separating, contact should enter. If when contact enters, the places it passes through should also perceive and know the traces of contact entering. If it truly perceives and knows, contact is constantly in the body and should constantly be known; why wait for them to join to be known?