Sending peace and blessings [durud, salam, salutations] upon our master, the master of the entire creation, the greatest of all Prophets and Messengers, Sayyiduna Muhammad al-Mustafa SallALLAHu ‘alayhi wa Sallam is not only a virtuous act, in fact it is a direct command from Allah to the believers.

Those who deem salawat [durud] as shirk and bid’ah should take heed from verses of the Qur’an where Allah’s curse is on those who insult, disrespect Sayyiduna al-Mustafa SallALLAHu ‘alayhi wa Sallam.

one of the best recommended books for durud is DALA’ILUL KHAYRAT BY Imam Muhammad ibn Sulayman al-Jazuli radiyALLAHU ‘anh and the famous Qasidah Burda sharif by Imam Sharaf ad-Din Muhammad al-Busiri radiyALLAHu anhu

if you would like to know more about the excellence of salat-o-salaam [durud sharif, salutations, blessings] read Sa’adatud Darayn fis-Salati ‘ala Sayyid al-Kawnayn SallALLAHu ‘alayhi wa SAllam by the great Imam Yusuf ibn Isma’il al-Nabhani radiyALLAHu ‘anh and al-Qawl al-Badi’ fis Salati ‘ala Habib al-Shafi’ SallALLAHu ‘alayhi wa Sallam by Imam as-Sakhawi radiyALLAHu ‘anh

some ahadith are mentioned below [article can be downloaded from http://www.nooremadinah.net/Documents/YaMohammad/Salat-o-Salam/Salat-o-Salam.asp]

It is completely within the Shari’ah (Islamic Law) to recite Salutations and Blessings upon Allah’s Messenger (sallallahu ‘alaihi wasallam) as is evident in the following Qur’aanic ayat : “Undoubtedly, Allah and His Angels send blessings on the Prophet (the Communicator of Unseen News), O you who believe ! Send upon him blessings and salute him fully well in abundance” (Surah al-Ahzab, Verse 56)

Almighty Allah in the Holy Qur’aan has enjoined the performance of many things by us such as Salaah, Fasting, Hajj etc. and has praised His Prophets and described their good qualities. He created Hadhrat Adam (‘alaihis salaam) and directed the Angels to do Sajda (prostration) to him. However, he does not say in any of His directions, “I (Allah) am doing it, therefore you should do likewise”. This honour was exclusively conferred upon our Beloved Nabi Hadhrat Muhammad (sallallahu ‘alaihi wasallam). Here, in the above verse, Almighty Allah at the very outset attributed Salawat (recital of blessings) on our Beloved Nabi Hadhrat Muhammad (sallallahu ‘alaihi wasallam), first to Himself (Sunnat-i-Ilaahi), then to His Angels (Sunnat-i-Malaa’ika), and after this enjoined on the Muslims (Sunnat-i-Mu’mineen) to do the same, by saying, “Undoubtedly, Allah and His Angels send blessings on the Prophet (the Communicator of Unseen News), O you who believe ! Send upon him blessings and salute him fully well in abundance”. There cannot be a greater honour for the Believers than this, who have been favoured with a share in this Divine performance with Almighty Allah and His Angels. 

It is stated in the commentary of the Qur’aan, Tafseer-i-Rooh al-Bayaan, “Some ‘Ulama are of the opinion that the meaning of Allah’s blessing is, to raise Hadhrat Muhammad Mustapha (sallallahu ‘alaihi wasallam) to Maqaam-i-Mahmood (Glorious Station), the place from where he will intercede to Almighty Allah on behalf of his Ummat; the Angels’ blessing means their prayer for enhancing the position of Hadhrat Muhammad Mustapha (sallallahu ‘alaihi wasallam) and beseeching forgiveness for his followers. Blessings on the path of the believers means to obey, love and eulogize him.” Tafseer-i-Rooh al-Bayaan further states that the honour and reverance shown to Hadhrat Muhammad (sallallahu ‘alaihi wasallam) is of a much greater degree than shown to Hadhrat Adam (‘alaihis salaam) to whom only Angels were made to bow down (in honour). For in honouring Hadhrat Muhammad Mustapha (sallallahu ‘alaihi wasallam) Almighty Allah has also attributed it to Himself, whereas in the case of Hadhrat Adam (‘alaihis salaam) Almighty Allah asked only the Angels to show honour.

Having established and expounded on the injunction of the Holy Qur’aan we quote a few Ahaadith of the Holy Prophet (sallallahu ‘alaihi wasallam) pertaining to Salawat and Salaam.

Imam Tibraani (rahmat allahi ‘alaih) has recorded this Hadith narrated by Hadhrat Abu Darda (radi allahu ‘anhu) :

The Holy Prophet (sallallahu ‘alaihi wasallam) said : “Increase your recitation of DUROOD on me on Friday because on this day Angels present themselves to me. There is no servant of Allah who recites SALUTATIONS upon me, except that his voice reaches me from wherever he is”. The Companions asked even after your departure ? “He replied, Yes after my departure too, because Allah has made it Haraam upon the earth to consume the bodies of the Prophets”. (Jila-ul Afhaam, by Ibn Qayyim)

“On Fridays recite the Salawat for me repeatedly ! The Salawat will be conveyed to me.” (Ibn Hibbann, Ibn Maaja, Abu Dawood)

When it was asked whether it would be conveyed to him after his Wisaal also, the Prophet (sallallahu ‘alaihi wasallam) answered, “Soil does not rot Prophets’ bodies. Whenever a Muslim says the Salawat for me, an Angel informs me of it and says, ‘So-and-so’s son, so-and-so of your Ummah sent his Salaam and prayed for you.'”

Sahl ibn Sa`d (radi allahu ‘anhu) narrates: Allah’s Messenger (sallallahu ‘alaihi wasalam) came out and met Abu Talha. The latter rose and went to him saying: “My father and mother be sacrificed for you, O Messenger of Allah! I see joy and delight in your countenance?” The Prophet (sallallahu ‘alaihi wasallam) said: “Yes, for Gabriel has just come to me saying: O Muhammad, whoever among your Community invokes blessings upon you once, Allah records for Him ten meritorious deeds, erases from his register ten evil deeds, and raises him ten degrees because of it.” (al-Sakhawi, al-Qawl al-badi` p. 107., al-Sakhawi said: “Our shaykh (Ibn Hajar) graded it hasan without doubt.”) 
 
 
in relation to the Messenger SallALLAHu ‘alayhi wa Sallam hearing us, then there is no doubt that wherever the ardent lovers are, the Messenger SallALLAHu ‘alayhi wa Sallam hears them, answers their prayers, removes difficulties, calamities [see al-Amnu wal Ula by Imam Ahmad Rida Khan al-Qadiri radiyALLAHu ‘anh, also available in English]
 
if the wretched would hear the Messenger SAllALLAHu ‘alayhi wa Sallam when they were in pits of a well in Badr, then what do you think about the close and chose servants of Allah – the Awliyah, the Sahabah and Ahlul Bayt and then what about the greatest of Prophets – the Messenger of Allah SallALLAHu ‘alayhi wa Sallam