If a person prostrates on his forehead and his nose does not touch the ground, is his prayer valid?

Question:
He says: Honorable Shaykh, may Allah grant you success, if a person praying leaves out some of the limbs and does not prostrate on them, such as the nose, is his prayer invalid and does he have to repeat it?

Answer:
The nose is not an independent limb; the face includes the forehead and the nose. So if he prostrates on his forehead, his prayer is valid. But if he prostrates on his nose and does not prostrate on his forehead, his prayer is not valid, because the nose is subordinate to the forehead. Yes, unless he has an excuse. Yes, but they say that if it is difficult for him to prostrate on his forehead, he does not prostrate but rather gestures with his head. Yes.