Takbeer of ‘Eid-ul Fitr

Recite: Allaahu akbar, Allaahu akbar, laa ilaaha ill-Allaah, Allaahu akbar, Allaahu akbar, wa Lillaahil-hamd (Allaah is Most Great, Allaah is Most Great, there is No god except Allaah, Allaah is Most Great, Allaah is Most Great, and all praise be to Allaah).

Or you can say Allaahu akbar three times, so you say: Allaahu akbar, Allaahu akbar, Allaahu akbar, laa ilaaha ill-Allaah, Allaahu akbar, Allaahu akbar, Allaahu akbar, wa Lillaahil-hamd (Allaah is Most Great, Allaah is Most Great, Allaah is Most Great, there is no god except Allaah, Allaah is Most Great, Allaah is Most Great , Allaah is Most Great, and all praise be to Allaah).

Both are permissible.

The time for this takbeer begins when the sun sets on the night of Eid (i.e., the night before) if it is known that the new month has begun when the sun sets, such as when the people have completed thirty days of Ramadaan, or when it is proven that the new moon of Shawwaal has been sighted. And it ends when the prayer begins, i.e., when they start the Eid prayer then the time for the takbeer ends.

Majmoo’ Fataawa Ibn ‘Uthaymeen, 16/269-272.