What is the evidence for invoking blessings upon the Companions in the prayer upon the Prophet (peace be upon him), and is it permissible to include them therein?

Praying for (or sending blessings upon) individuals other than prophets is a matter of scholarly disagreement. Some scholars permit it independently, citing Allah's saying: "He it is Who prays for you, and His angels, that He may bring you forth from darkness into light; and He is Merciful to the believers" (Qur'an 33:43), and based on the action of the Prophet, peace be upon him. Some, however, restrict it to not being adopted as a regular slogan. As for praying for them dependently, there is absolutely no harm in it. The imams have agreed on the permissibility of praying for the Companions dependently, but they differed on its permissibility independently. Mentioning the family (Aal) in prayer is established by text, and praying for the Companions (Sahb) is by analogy, in addition to it being a contradiction to the people of innovation.