Literal and figurative status should not be assigned to a word-form in isolation from every context. An expression may be conventionally assigned to one sense in one domain and to another sense in another domain.
Case 1: Consider “ṣalāh” in ordinary lexical discourse where it can denote supplication.
Case 2: Consider it in juristic discourse where it denotes the prescribed act of worship.
Case 3: Consider a contextual use of the same term for supplication within a discourse governed by its religious technical sense.
The third case needs analysis of the relation between supplication and the broader ritual, not merely a comparison of surface word-forms.