Is prostration of recitation obligatory upon a worshipper performing تحية المسجد (greeting of the mosque prayer) if he is with the congregation?

Prostration of recitation (sujood at-tilawah) is supererogatory, not obligatory. If someone is performing prayer and hears a verse of prostration, he should not prostrate with the reciter; otherwise, his prayer would become invalid. Some jurists are of the opinion that he should perform it after concluding his prayer.