四分比丘戒本疏 2.85

2.85

第五十七、然火戒。「除時因緣」者，准律，不但露燃有犯，縱非露燃應犯吉羅。是故律中除時因緣，謂為病比丘煮羹飯乃至染衣等不犯。蓋為此事屏然不犯，露然壞地何得不犯？明知不病者，屏燃亦犯小罪。准律教人燃，應言「看是知是」也。

The fifty-seventh, the precept on lighting fires: 'Except for timely reasons'—according to the Vinaya, not only is lighting a fire in the open an offence, but even lighting a fire not in the open should be a duṣkṛta offence. Therefore, 'except for timely reasons' in the Vinaya means cooking broth and rice for an ill monk, up to dyeing robes, etc., which are not offences. Because lighting a fire in a screened place for these purposes is not an offence, but how could lighting a fire in the open and damaging the ground not be an offence? Clearly one knows that for one who is not ill, lighting a fire in a screened place also incurs a minor offence. According to the Vinaya, when instructing another to light a fire, one should say, 'See to this; know this.'