About midnight (kata de mesonuktion). Middle of the night, old adjective seen already in Mark 13:35 ; Luke 11:5 which see. Were praying and singing (proseucomenoi umnoun). Present middle participle and imperfect active indicative: Praying they were singing (simultaneously, blending together petition and praise). Humnew is an old verb from umno (cf. Isaiah 12:4 ; Daniel 3:23 ). Paul and Silas probably used portions of the Psalms (cf. Luke 1:39Luke 1:67 ; Luke 2:28 ) with occasional original outbursts of praise. Were listening to them (ephkrownto autwn). 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.