Reference: Fataawa Ramadhaan – Volume 2, Page 947, Fatwa No.935
Fiqh al-Ibaadaat libni ‘Uthaymeen – Page 215
Question: We would like to know what a Muslim says once the moon of Shawwaal has been sighted [up until] before the ‘Eed prayer?
Response: That which is befitting is to increase in [reciting] the takbeer (the saying of: Allaahu Akbar (Allaah is the Greatest)), and the tahleel (the saying of: laa ilaaha ill-Allaah (there is none truly worthy of worship except Allaah)), and the tahmeed (the saying of al-hamdu-lillaah (all Praise is for Allaah)), for that which Allaah (Tabaarak wa Ta’aala) [mentions]: