佛說觀佛三昧海經 6.10

6.10

「既習慈已次當行悲，悲者見眾受苦，如箭入心如破眼目，心極悲苦遍體雨血欲拔彼苦，如此悲者有百億門，廣說如大悲三昧。

"Having practiced loving-kindness, next one should cultivate compassion. As for compassion: seeing sentient beings suffer pain is like an arrow piercing one's heart, like having one's eyes destroyed; one's mind is profoundly grief-stricken and one's whole body rains blood, wishing to eradicate their suffering. Compassion of this kind has a hundred billion gates; it is explained extensively as in the samādhi of great compassion.