Acts 12:5

ἐτηρεῖτο ἐν τῇ φυλακῇ, was kept [guarded] in the prison. Another indication of the intended longer duration of the imprisonment, and that he was not arrested on the day of the Paschal sacrifice with the purpose of being brought forth on the morning of the 15th of Nisan, as some have maintained.

προσευχὴ δὲ ἦν ἐκτενῶς γινομένη κ.τ.λ., but prayer was earnestly made by the Church unto God for him. The adverb ἐκτενῶς is thus used in LXX. of earnest crying unto God. Joel 1:14; Jonah 3:8. So Jdt 4:12 καὶ ἐβόησαν πρὸς τὸν θεὸν Ἰσραὴλ ὁμοθυμαδὸν ἐκτενῶς τοῦ μὴ δοῦναι εἰς διαρπαγὴν τὰ νήπια αὐτῶν. The prayers of the Church were offered by assemblies of Christians meeting in various private houses (see Acts 12:12), for the persecution would now render public Christian services dangerous, as we know was often the case in the early days of Christianity.