Rasulullah (Sallallahu alayhi wasallam) said: “Shaitaan urinates in the ear of a person who sleeps until the morning.”
Commenting on this Hadith, Allaamah Abdul Wahha ab Sha’raani (Rahmatullah alayh), the illustrious Shaafi’ authority of the 10th Islamic century, said: “This actually (i.e. literally) happened to one of my companions. Urine was flowing from both ears onto his neck. In my presence he washed it. He used to believe that this Hadith had an allegorical meaning (i.e. it does not literally mean urine).
Therefore it is proper for one who sleeps until the morning to wash his ears thereby purifying them from the urine of shaitaan even if he does not see the urine (physically).”

(End of Allaamah Sha’raani’s comment)
Sleeping until late in the morning which results in missing Fajr Salaat, is exceptionally harmful both spiritually and physically.
When Rasulullah (Sallalla alayhi wasallam) has informed us that shaitaan urinates in the ears, it does not behove a Mu’min to doubt the Truth which is information provided to the Nabi by Allah Ta’ala.
Even if the urine of Iblees is not physically perceived, seen or felt, the detrimental effects of his filth are extremely harmful for both the physical health and for spirituality.
Shaitaan is a jinn. The jinn have been granted the power of assuming a variety of forms. They are able to possess the entire human body by penetrating into the body. Just as the whole body of the jinn is invisible to us, and able to reside within the human body without being visible, so too is shaitaan’s urine.
There should therefore be no scepticism when informed by Rasulullah ( S a l l a l l a h u a l a y h i wasallam) that Iblees urinates in the ears of those who sleep away their  Fajr Salaat.