Is it permissible to invoke blessings upon someone other than the Prophet (peace be upon him), such as saying: "O Allah, bless so-and-so"?

Scholars have differed regarding the permissibility of invoking blessings (ṣalāt) upon someone other than the Prophet (peace be upon him) by someone other than the Prophet (peace be upon him) individually, with two views: prohibition (Malik and Ash-Shafi'i) and permissibility (Ahmad and most of his companions). Those who prohibit it cite the saying of Ibn Abbas: "I do not know of invoking blessings (ṣalāt) upon anyone by anyone except upon the Messenger of Allah (peace be upon him)," which he said when the Shi'ah appeared and invoked blessings upon Ali but not on others. Those who permit it cite what was narrated from Ali that he said to Umar: "May Allah invoke blessings upon you (ṣallā Allahu 'alayka)." Invoking blessings upon someone other than the Prophet, if it is not done in an exaggerated manner or as a specific emblem for someone other than the Messenger, is a type of supplication, and there is nothing in the Quran or Sunnah to prevent it. They cite as evidence: "It is He who invokes blessings upon you, and His angels" (Quran 33:43), and "Indeed, the angels invoke blessings upon one of you," and "May Allah invoke blessings upon you and the body you inhabited." There is no disagreement that the Prophet (peace be upon him) invokes blessings upon others, as in his saying: "O Allah, invoke blessings upon the family of Abu Awfa," and he invokes blessings upon others as a subordinate to him, such as: "O Allah, invoke blessings upon Muhammad and the family of Muhammad."