They are deaf, dumb and blind. They will not return (to the path)

Summun Bukmun ‘Umyun fahum laa yarji’oon’

They are deaf, dumb and blind. They will not return (to the path)

“God hath set a seal on their hearts and on their hearing, and on their eyes is a veil; great is the penalty they (incur).”

The Tafsir of Ibn Kathir says that the first group is like one who is blind and deaf, while the second group is like he who sees and hears. Thus, the disbeliever is blind from the truth in this life and in the Hereafter. He is not guided to goodness, nor does he recognize it. He is deaf from hearing the proofs, thus he does not hear that which would benefit him. 

On the other hand, the believer is smart, bright and clever. He sees the truth and distinguishes between the truth and falsehood. Thus, he follows the good and abandons the evil. He hears and distinguishes between the proof and scepticism. Therefore, falsehood does not overcome him.

1150. Ibn `Umar and Abu Hurairah (May Allah be pleased with them) reported: We heard the Messenger of Allah (PBUH) saying (while delivering Khutbah on his wooden pulpit), “Either some people (i.e., hypocrites) stop neglecting the Friday prayers, or Allah will seal their hearts and they will be among the heedless.”
[Muslim].

Alhamdulillah, we are Muslims with the seal lifted from our hearts so we ultimate goal and the actions that lead to it should be clear… inshAllah.

 “No one is safe from misguidance. So remember to constantly ask Allah to keep you on the straight path” - Saalih Luhaydaan

A du’aa that he mentioned pertaining to this is:

يَا مُقَلِّبَ الْقُلُوبِ ثَبِّتْ قَلْبِى عَلَى دِينِكَ

Yaa Muqallibal Quloob Thabbit Qalbee ‘alaa Deenik.

“Oh turner of the hearts (Allah, the Most High), keep our hearts firm on your religion“

[Authenticated by al-Albanee]

If Allah wills, He can seal the heart from guidance. “All the hearts of the offspring of Adam are between two fingers of Ar-Rehman’s Fingers, as one heart. He turns it (in any direction) as He wills. Then Allaah’s Messenger said, “O Allaah! The Turner of the hearts, turn our heart towards Your obedience.” [Saheeh Muslim]

The Prophet (sallahAllaahu alayhi wasallam) used to do so, and taught us to do so, as in the hadeeth of Umm Salamah by Shihr who said : ‘I said to Umm Salamah : ‘O Mother of the Believers, what is the duaa’ which the Prophet (sallahAllaahu alayhi wasallam) would supplicate the most while in your presence? ’

So she said : ‘The frequent supplication of his was :

يَا مُقَلِّبَ الْقُلُوبِ ثَبِّتْ قَلْبِى عَلَى دِينِكَ

“O, Turner of the hearts, turn our hearts to Your obedience.”

And also reported by Imaam Ahmad , from the hadeeth of ‘Aisha (radhiyaAllaahu anha): ‘The Dua’ which the Prophet (sallahAllaahu alayhi wasallam) used to supplicate with a lot…’ then she mentioned it. - Silsilah as-Saheeha of Al-Albaanee