坐禪三昧經 1.91

1.91

是故行者常當專心令意不散，既得見佛請質所疑，是名念佛三昧。除滅等分及餘重罪。

Therefore, the practitioner should constantly focus the mind, keeping the intention from scattering. Having seen the Buddha and questioned him about one's doubts, this is called the recollection-of-the-Buddha samādhi. It eliminates equal-part [afflictions] and other grave sins.