四分律行事鈔資持記 3.89

3.89

九中。不禮皆據對別，不約對僧。注出所以。敬處尊者，即指大衣。恐彼不知，故須陳意；應云：某甲身著大衣，不得設禮。

In the ninth [part], not prostrating is in all cases based on facing an individual, not facing the Saṅgha. The note provides the reason. 'The revered object of respect' refers to the great robe. Fearing that the other person does not understand, one must state one's intention; one should say: 'So-and-so is wearing the great robe on his body, and may not perform prostrations.'