Vincent's NT Word Studies
4. Whiles it remained, was it not thine own (ouci menon soi emene). A play on the words. Lit., remaining, did it not remain to thee? Rev., very happily, whiles it remained, did it not remain thine own?Conceived (eqou). Lit., put or fixed. Wherefore didst thou fix this deed in thy heart? - i.e, resolve upon it.
Robertson's NT Word Studies
5:4 {Whiles it remained} (menon). Present active participle of mend, unsold, Peter means. {After it was sold} (praqen). First aorist passive of pipraskw, to sell. {How is that thou hast conceived} (ti hoti eqou). _Quid est quod_. See #Lu 2:49. See also #Ac 5:9. Second aorist middle indicative second person singular of tiqemi. The devil filled his heart (verse #3), but all the same Ananias did it too and is wholly responsible.