What is the ruling on praying Eid with a group who, out of ignorance, reduce the number of their takbeers from five to three, and is it valid to pray with them, knowing that they commit many errors in matters of Islam?

The majority of scholars hold that the number of Eid takbirat (glorifications) is seven in the first rak'ah (unit of prayer) and five in the second, excluding the takbir for standing. This is the view adopted by the Imams of the three schools of thought: Malik, Ash-Shafi'i, and Imam Ahmad, as well as many Companions and jurists from the Tabi'in. Conversely, Abu Hanifah and Ath-Thawri are of the opinion that there are three takbirat in each of the two rak'ahs. Therefore, the questioner should explain to them the manner of Eid prayer and the number of its takbirat according to the opinion of the majority of scholars, and then proceed to pray with them.