What is the ruling on praying behind an Imam who says "Allah Akban" instead of "Allah Akbar" in the opening Takbir (Takbirat al-Ihram), knowing that he sometimes pronounces it correctly, and it is not possible to go to another mosque?

Scholars differ on the validity of an althagh's imamate (leading prayer) across two opinions:

Most scholars hold that his imamate is invalid because his recitation of Al-Fatiha is incorrect, likening him to an illiterate person who cannot recite it properly.

Others maintain the validity of his imamate because he is not negligent; this is the best he can do. They cite the noble verse: "Allah does not burden a soul beyond its capacity" (Quran 2:286).

Shaykh Ibn 'Uthaymeen preferred the opinion that his imamate is valid, while also emphasizing caution and selecting someone free from defects if possible.