In four Surahs of the Qur'an (Alif Lam Meem Sajdah. Ha Meem Sajdah, Najm and.’Alaq) there is one verse which is called verse of sajdah. Anybody who recites that verse or listens to it must do sajdah at the end of that verse. If while listening to it he was reciting it also, he should do two sajdahs.
The place where he does the sajdah must be mubah (not ghasbi) and the place of forehead should not be more than 3" lower or higher than the place of knees or toes. The rules about the things upon which sajdah of prayer is allowed must be followed in this Sajdah also.
It is not wajib to say any dhikr in this sajdah. Still it is sunnat to recite the following dhikr:
La ilaha illal-lah haqqan haqqa; la-ilaha-illal-lahu Imaanan wa Tasdiqa; La ilaha illal-lah ‘ubudiyatan wa riqqa; Sajadtu laka ya Rabbi ta’abbudan wa riqqan; La mustankifan wa la Mustakbiran; bal ana ‘abdun dhalilun da’ifun kha’ifun mustajir.
It is not necessary to do wudhu etc., or to face towards qibla in this sajdah.