What is the ruling on the prayer of those who lift their foreheads off the ground during prostration, and what is your advice to them?

The forehead must be firmly placed on the ground during prostration (sujud), based on what was narrated by Anas ibn Malik (may Allah be pleased with him): "We used to pray with the Prophet (peace be upon him) in intense heat. If one of us was unable to firmly place his forehead on the ground, he would spread his garment and prostrate on it." Merely touching the forehead to the place of prostration is not sufficient; therefore, the prostration and the prayer are not valid.