Shaikh Saalih al-Fawzan hafidhuhallah was asked:
Oh Virtuous Shaikh, this questioner is saying, ‘we hope from the Shaikh [may Allah preserve him] some advice to the general Ummah specifically about April Fools which repeats year after year.
“This is imported in general from the false customs and it is not from the actions of the Muslims. Lying is not allowed. Not in April or in other than it. Lying is haram. Lying upon Allah, lying upon the Messenger (ﷺ), lying upon the people is haram. It is a major sin from the major sins. Allah forbade lying, prohibited it, and threatened the liars. It is not allowed in any time. Yes”.
Shaikh Ibn ul-‘Uthaymeen rahimahullah said:
“…In this occasion, I warn my Muslim brothers from what some of the foolish ones do of April Fools. I think it is soon. This lie which came from the Jews, Christians, Zoroastrians, and the people of disbelief, then it is lying and lying is prohibited legislatively. It is an imitation of the disbelievers and imitation of the disbelievers is prohibited. The Prophet (ﷺ) said:
مَنْ تَشَبَّهَ بِقَوْمٍ, فَهُوَ مِنْهُمْ
He who imitates any people (in their actions) is considered to be one of them
[Saheeh Sunan Abi Dawood no.2031]
Shaikhul Islaam ibn Taymiyyah rahimahullah said the chain is Jayyid. The least of the situations is that it is prohibited even if the apparent [meaning of the Hadith] necessitates disbelieve by imitating them…Fourth, most times this filthy lying includes consuming the wealth in falsehood or scaring the Muslims. Sometimes he lies and lies to the people of the house saying so and so said, ‘you will be visited by a group today’. So they cook a lot of food and meat and what resembles that. Or sometimes, they inform them of an affair that scares them. Like he says, your guardian was run over by a car or the likes, which is not allowed even outside this situation [i.e. April Fools]. So it is upon the Muslim to fear Allah, the Exalted and to be mighty through his religion, proud of it, pleased with it so that the enemies may have awe of the Muslims and respect him…”
[Fatawa Noor ‘ala Darb no. 34]
Faisal Ibn Abdul Qaadir Ibn Hassan