四分律比丘含注戒本 2.427

2.427

(The Buddha was in Śrāvastī. Kālodayin, mindful of the previous precept stating 'one should sit where one's hand reaches the door,' immediately sat behind the door leaf talking together with the upāsikā. Bhikṣus heard their talk, criticized and censured him, and reported it to the Buddha, who thereupon rebuked him and formulated the precept.)