Surah 33 (Al‑Ahzaab), Ayah 56 sends blessings to the Prophet (pbuh)
إِنَّ الله وَمَلائِكَتَهُ يُصَلُّونَ عَلَى النَّبِيِّ
يَا أَيُّهَا الَّذِينَ آمَنُوا صَلُّوا عَلَيْهِ وَسَلِّمُوا تَسْلِيمًا
Verily Allah and His angels send blessings on the Prophet.
O you who believe! send blessings on him [Muhammad] and greet him with the fitting salutation.
Commentary
Allah sends His blessings “salawaat”صلوات on the Prophet (pbuh), and the angels implore Allah to send His blessings on him [the Prophet]. The believers are also commanded to invoke Allah to send His blessings on him too. The Muslims asked the Prophet (pbuh): “How are we to seek blessings on you?” The Prophet (pbuh) answered, “Say: 'O Allah, send blessings on Muhammad and upon Aali Muhammad,” thus he included Ahlul Bayt within the Salawaat for him.
Bukhari, Vol. 3, Page 127, quotes Muhammad (pbuh) prohibiting to say an incomplete Salawaat. When asked, the Prophet replied,
“Do not just say: `O' Allah! Send blessings on Muhammad' and stop there, instead say, `Allahumma Salli ala Muhammad wa Aali Muhammad'”
meaning always to include Aali Muhammad with the Salawaat.
In Conclusion
Ibn Hajar, (Al‑Sawaa'iq, Page 88) quotes the well‑known poem composed by Al‑Shafi'i (head of Shafi'i Madh'hab), and so does Sayooti, in his interpretation of Ayah of Tat'heer, as follows:
يا آل بيت رسول الله حبكم فرض من الله في القرآن أنزله
كفاكم من عظيم الشأن انكم من لم يصلي عليكم لا صلاه له
Roughly translated Al‑Shafi'i says:
Oh loving you Ahlul Bayt is such
That it is a duty the Quran had established
Suffice it that so privileged your distinction is
That Salat becomes invalid if Salawaat is not invoked for you.
source : http://www.islamicbooks.info
