Salaamu Alaykum Shiekh,
I have a question about Pharoah (Fir'aoun).
My parents said me that Pharoah use to worship ALLAH (The Merciful) the whole night and moreover up side down in hunbleness, but then in day time he would turn into tyrant.
Is there any evidence for his worshipping at night time?
Jazaak ALLAHu Khair.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

We have not come across any source for this statement among the books of the scholars that we have at hand, and we think this statement has no basis.

Moreover, a person who worships Allaah by night and humiliates himself to Him is often a humble person to Him by day, and humble to His Creation, and not a tyrant and oppressor who says to the people like what Allaah Says on the tongue of Pharaoh (what means): {O eminent ones, I have not known you to have a god other than me.}[Quran 28:38] Allaah also Says on the tongue of Pharaoh (what means): {And said, “I am your most exalted lord.”}[Quran 79:24]

Besides, what is the purpose of an act of worship whose outcome is not the fear of Allaah? Allaah Says (what means): {O mankind, worship your Lord, who created you and those before you, that you may become righteous.}[Quran 2:21]

Therefore, there is no evidence for what you mentioned in the question. Pharaoh is nothing but the leader of arrogant and oppressive tyrants.  

Allaah Knows best.