四分律比丘含注戒本 2.145

2.145

(This means that each time one turns over or one's flank touches the couch, a prāyaścittika is incurred. Regarding non-offense: if one previously did not know; if one stayed after having spoken [to him] and [the other] previously made space for him; if the space is wide and does not obstruct; if a relative or acquaintance instructed him, saying, “Just spread it, I will speak to the owner myself”; if one falls to the ground; if one is sick, turns over, and falls upon it; if one is restrained by physical force; if one is locked up; or due to the two perils of life and chastity—none of these constitute an offense.)