佛說目連問戒律中五百輕重事經 1.96

1.96

問：「夏中坐，若為三寶事、若疾病、種種眾難，得移坐不？」答：「得坐，當白眾中，受三十九日法。三十九日已有事便出界。三十九日法，三十九日滿得還。一若不得，亦可彼處受歲無犯。若坐初不受，臨行時亦得受。若坐已滿三十九日者，事便出界，不須復受。若不還，亦得於彼處受歲。」

Question: "When observing the retreat during the summer, if because of affairs of the Three Jewels, illness, or various difficulties of the assembly, may one move the retreat?" Answer: "Retaining the retreat, one should announce it in the saṃgha and receive the thirty-nine-day rule. When thirty-nine days have elapsed, having business, one then leaves the sīmā. Under the thirty-nine-day rule, when the thirty-nine days are fulfilled one may return. Or if one cannot, one may also receive monastic age in that other place without offense. If not received at the beginning of the retreat, it may also be received when about to depart. If one has already observed the retreat for thirty-nine days, then having business one leaves the sīmā, there is no need to receive it again. If one does not return, one may also receive monastic age in that other place."