Is it obligatory to place the nose on the ground during prostration (sujud) in prayer, and what is the ruling on not doing so, and what are the legal proofs for its obligation?

Scholars have differed on the ruling of placing the nose on the ground during prostration (sujud). Al-Shafi'i, along with some narrations from Malik and Ahmad, held that it is not obligatory. Ibn Jubayr, Al-Nakha'i, Ishaq, and other narrations from Malik and Ahmad, held that it is obligatory. As for Abu Hanifa, he is of the view that what is obligatory is placing either the forehead or the nose. The preponderant view is that it is obligatory, due to the saying of the Prophet, peace and blessings be upon him: "I have been commanded to prostrate on seven bones: the forehead – and he pointed to his nose – the hands, the knees, and the ends of the feet," and due to his saying: "Pray as you have seen me praying."