Reading the Mu‘awwithaat and wiping over the body after prayer is not legislated
14-2-2015 | IslamWeb
Question:
Assalaamu'alaykum, My question is: When we read surah al-Ikhlâs and the Mu'awadhatayn after each salaah do we have to blow in our hands and wipe over our body just like the Prophet (SAW) did before he retired to bed? Jazaak'Allah kheir
Answer:
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.
Blowing in one's hands and wiping over one's body or face after reading the three Soorahs Al-Ikhlaas and the Mu‘awwithatayn (Quran 112, 113 and 114) after the prayer is not instituted in the religion because, as far as we know, this is not reported from the Prophet, sallallaahu ‘alayhi wa sallam.
This has only been report with regard to when going to bed; ‘Aa’ishah 
said that whenever the Prophet, sallallaahu ‘alayhi wa sallam, went to bed, he would blow upon his hands and recite Soorahs of Al-Ikhlaas and the Mu‘awwithatayn and then he would pass his hands over his face and whatever he could reach of his body. [Al-Bukhari]
Another narration reads: "…then he would wipe over whatever he could reach of his body, starting by wiping over his head and face, and the front of his body, doing that three times."
This was also reported about Ruqyah. ‘Aa’ishah said that whenever the Prophet, sallallaahu ‘alayhi wa sallam, suffered from an ailment, he would recite the Mu‘awwithaat (Quran 112, 113 and 114) and blow. When his pain became very severe, ‘Aa’ishah said that she would recite over him and take his hand and wipe them over him seeking their blessing. [Al-Bukhari and Muslim]
Therefore, as far as we know, it was not reported that the Prophet, sallallaahu ‘alayhi wa sallam, used to do that after the prayer. Indeed, the best guidance is the guidance of Muhammad, sallallaahu ‘alayhi wa sallam. Ibn Hajar Al-Haythami 
said about blowing in one's hands and wiping over one's face after exalting the mention of Muhammad, sallallaahu ‘alayhi wa sallam: "If someone does it after exalting his mention, sallallaahu ‘alayhi wa sallam, or at other times when it is not a Sunnah to blow in one's hands, then he has indeed committed what is not recommended, so it is better to avoid it." [End of quote - excerpted from Al-Fataawa Al-Hadeethiyyah]
Allaah Knows best.