Contrary to the opinion of the public, because the public instructs the one who prays while lying down to pray while lying on his back, whereas the Noble Prophet (peace and blessings be upon him) instructed the one who prays while lying down to pray while lying on his side.

Sayyiduna Imran bin Husain (may Allah be pleased with him) narrates that I was suffering from hemorrhoids, so I asked the Prophet (peace and blessings of Allah be upon him) about the manner of performing prayer. The Prophet (peace and blessings of Allah be upon him) said: "Pray standing; if you are not able to pray standing, then pray sitting; if you are not able to do even that, then pray lying on your side." In the narration of Imam Ibn Mubarak (may Allah have mercy on him), the word "hemorrhoids" is mentioned (the meaning in both is the same).