Assalaamu alaikum, I have read that Sunnah Muakkada is very important practice for Muslims and if anyone leave this sunnah (with no due reason) than such person will be deprived of Shafa'a (intercession) of Prophet Muhammad (SallALLAH Alaihi wa Sallam) on the day of Qayamah. So I want to know whether this thing is true or not? Kindly give us Daleel as much as you can so that we have to reply to our people in locality. Jazaak ALLAHU Khair.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

If you mean by "Sunnah Mu’akkadah" (emphasized traditions, i.e. acts that Prophet Muhammad, Sallallaahu 'alayhi wa sallam, always used to do) the regular voluntary prayers before and after the obligatory prayers, then there is no doubt that performing these Sunnah prayers regularly is important because they are acts that bring one closer to Allaah and cause Him to love him. The Prophet, sallallaahu ‘alayhi wa sallam, said in a Qudsi Hadeeth: “My slave keeps on doing what brings him closer to Me by performing the Nawaafil (voluntary good deeds) until I love him…” [Al-Bukhari]

Moreover, Sunnah prayers make up for the deficiency in the obligatory prayers on the Day of Judgment. The Prophet, sallallaahu ‘alayhi wa sallam, said: “Our Lord, The Exalted, will say to the angels – though He knows better - ‘Look to the prayer of My slave and see whether he has offered it completely or incompletely.’ If it is complete, it will be recorded as complete. If it is incomplete, He will say: ‘See if My slave offered voluntary prayers.’ If he offered voluntary prayers, He will say: ‘Complete his obligatory prayer with his voluntary prayer.’” [Abu Daawood]

As for the claim that whoever fails to observe the Sunnah prayers will be denied the intercession of the Prophet, sallallaahu ‘alayhi wa sallam, we do not know of any evidence from the religion to support that claim. It has been authentically reported that the Prophet, sallallaahu ‘alayhi wa sallam, stated that whoever sincerely testifies that no deity is worthy of worship but Allaah, he will benefit from his intercession on the Day of Resurrection, and he, sallallaahu ‘alayhi wa sallam, did not stipulate the observation of Sunnah prayers. The Prophet, sallallaahu ‘alayhi wa sallam, said: “The happiest person with my intercession on the Day of Resurrection is the one who said, 'La ilaaha illa Allaah (no deity is worthy of worship but Allaah),' sincerely from his heart.” [Al-Bukhari]

The Prophet, sallallaahu ‘alayhi wa sallam, said that even those who have committed Kabaa’ir (major sins) will not be denied his intercession on the Day of Judgement. Anas ibn Maalik reported that the Prophet, sallallaahu ‘alayhi wa sallam, said: “My intercession will be for those from my Ummah who have committed major sins.” [Abu Daawood, At-Tirmithi and others]

For more benefit, please refer to Fatwa 182151.

Allaah Knows best.