{About midnight} (kata de mesonuktion). Middle of the
night, old adjective seen already in  Mr 13:35  Lu 11:5  which
see. {Were praying and singing} (proseuchomenoi humnoun).
Present middle participle and imperfect active indicative:
Praying they were singing (simultaneously, blending together
petition and praise). Humne(935c) is an old verb from humnos (cf.
 Isa 12:4  Da 3:23 ). Paul and Silas probably used portions of
the Psalms (cf.  Lu 1:39f.,67f.  2:28f. ) with occasional
original outbursts of praise. {Were listening to them}
(ep(886b)ro(936e)to aut(936e)). Imperfect middle of epakroaomai. Rare
verb to listen with pleasure as to a recitation or music (Page).
It was a new experience for the prisoners and wondrously
attractive entertainment to them.