首楞嚴義疏注經 5.384

5.384

身子入定於恒河岸，為鬼所掌，出定頭痛，佛語之曰：「汝若無定，身應碎壞。」今我亦爾，將恐退失所證道果。

Śāriputra was sitting in samādhi on the bank of the Ganges when he was struck with a fist by a demon. When emerging from samādhi his head ached, and the Buddha said to him: 'If you were not in samādhi, your body would have shattered.' Now I was also like this, fearing that I might regress and lose the fruit of the Way I had realized.