What is the legal ruling for saying "Subhanahu wa Ta'ala" (Glorified and Exalted be He) after the word "Allah," and "Al-Tasliyah" (invoking blessings and peace) after mentioning Muhammad, and "Al-Taraddi" (invoking Allah's pleasure) upon the Companions after mentioning their names, and "Al-Tarahhum" (invoking Allah's mercy) upon the deceased righteous, and is it obligatory or recommendable, and what is the reward for that?

Using "Subhanahu wa Ta'ala" (Glorified and Exalted be He) after the majestic name of Allah is commendable, increasing remembrance and praise of Allah. Sending blessings upon the Prophet (peace be upon him) is obligatory when he is mentioned, according to some scholars, and a Sunnah according to the majority. It is obligatory once in a lifetime, and anything beyond that is commendable. Expressing satisfaction and seeking mercy for the Companions and the righteous is commendable. The reward for this is recompense from Allah and the realization of the quality of faith, as Allah Almighty says: "And those who came after them say, 'Our Lord, forgive us and our brethren who preceded us in faith and put not in our hearts [any] resentment toward those who have believed. Our Lord, indeed You are Kind and Merciful.'" [Al-Hashr:10], and as the Prophet (peace be upon him) said: "Whoever sends blessings upon me once, Allah will send blessings upon him tenfold." And it must be said "salat" (blessings) upon the Prophet, not "tasliyah."