Sheikh Hânî al-Jubayr, judge at the Jeddah Supreme Court
Allah has commanded us to invoke Allah’s blessing upon His Prophet (peace be upon him). Allah says: “Allah and His Angels send blessings on the Prophet: O you who believe, send ye blessings on him, and salute him with peace.” [Sûrah al-Ahzâb: 56]
Therefore, when we say sallâ Allah `alayhi wa sallam “may the peace and blessings of Allah be upon him”, we are following the Qur’ânic injunction.
When we beseech the salâh “blessings” of Allah upon him, we are requesting from Allah to mention the Prophet (peace be upon him) in His exalted assembly with honor and praise.
Our offering of salutations of peace (salâm) is also a supplication from us for him to be in peace and free from all affliction.
When we make mention of his family and Companions along with him, we mean by his family his relatives who follow his religion, and by his Companions the people who accompanied him and believed in his message. There are many hadîth that mention the Prophet’s family. Indeed, among the clearest of these is that we are commanded to mention his family in our daily prayers in our tashahhud.
As for the Companions, they have the honor of being the ones who conveyed the religion to all those who came after them. Allah has informed us that He sends blessings (salâh) upon His believing servants. Allah says: “He it is who sends blessing on you all, as do His angels” [Sûrah al-Ahzâb: 43].
About the salutation of peace (salâm), Allah says: “Their salutation on the Day they meet Him will be ‘Peace’.”
The most worthy of people for this salutation are the Companions of the Prophet (peace be upon him).
We have already made clear that we invoke Allah's peace and blessings of upon the Prophet’s in obedience to Allah’s command: “O you who believe, send ye blessings on him, and salute him with peace.” [Sûrah al-Ahzâb: 56]
Allah’s saying: “Send ye blessings” means to say: “sallâ Allah `alayh”. And His saying: ‘salute him’ means to say: “wa sallam”.
The Companions followed this command, and whenever they heard the name of the Prophet (peace be upon him) they used to say these words. In every hadîth cited in the sourceworks you will find these words invoked after mention of the Prophet (peace be upon him) is made.
When we include His Companions we mean only to offer the same supplication for the Companions. This is, therefore, a permissible supplication in and of itself. It does not need further evidence.
It is the same as if a person says: “O Allah, protect me and bless me” and adds: “…and protect and bless so-and-so”. In the same way, we invoke Allah’s blessings and send salutation to the Companions. We already mentioned that Allah does so for every righteous person. The Muslim says in his tashahhud in every prayer: “Peace be upon us and upon Allah’s righteous servants”.
This a supplication the Muslims put into practice that does not need specific evidence. Furthermore, this issue is a matter of consensus (ijmâ`). Consensus, in Islamic Law, is evidence in and of itself.
Al-Hasan al-Basrî, the eminent scholar from among the Successors, used to say: “O Allah bestow your blessings (salâh) upon Muhammad, his family, his Companions, his wives, and his supporters”. This is mentioned by al-Qâdî `Iyâd in his book al-Shifâ.
May Allah guide us all.
Source: Islam Today