首楞嚴義疏注經 5.110

5.110

佛告阿難：「吾今以手左右各牽，竟不能解。汝設方便，云何解成？」阿難白佛言：「世尊！當於結心解即分散。」佛告阿難：「如是，如是。若欲除結，當於結心。」

The Buddha said to Ānanda, "I have now pulled left and right with my hands, but in the end it cannot be untied. If you were to devise an expedient means, how would the untying be accomplished?" Ānanda said to the Buddha, "World-Honoured One! It must be untied at the heart of the knot, and then it will come apart." The Buddha said to Ānanda, "So it is, so it is. If you wish to remove the knot, you must do so at the heart of the knot."