A short reminder to those seeking knowledge concerning the aspect of taqwá, since this is a useful tool long forgotten by many of those who enter themselves into the various sciences of this noble, pure Religion.
Whosoever loves that Allāh should open-up his heart for him and grant light to him, then let him abandon speech about that which does not concern him, and abandon sins and turn away from disobedience.
Allāh – the Most Perfect, Most High – said:
“O you who believe! Have taqwá (fear) of Allāh, and believe in His Messenger, and He will bestow upon you a double portion of His Mercy, and He will provide you with a light by which you will walk.’’ 
Allāh – the Most High – also said:
“O you who believe! If you have taqwá of Allāh, He will give you a Furqān (criterion to judge right and wrong).” 
Al-Ḥāfiẓ Ibn Kathīr (d.777H) – raḥimahullāh– said:
“Ibn ʿAbbās, al-Suddī, ’Ikrimah, ad-Dahhaak, Qatādah, and Muqaatil Ibn Hayyaan all said about “Furqān” that it means: a way out (from difficulty). Mujāhid added: A way out (from difficulty) both in this world and in the Hereafter. In a narration from Ibn ʿAbbās, he said: It means: salvation; and in another narration from him: being helped. Muḥammad Ibn Ishāq said that it means: a criterion to judge between truth and falsehood. This explanation from Ibn Ishāq is the most general of what has preceded, and it is a necessary consequence of it. Since whoever has taqwá of Allāh by obeying His Commands and abandoning that which he has prohibited, will be given the ability to recognize the truth from falsehood. This will be the cause for his salvation, his being helped; and the cause for his worldly affairs being made easier, and his happiness on the Day of Judgement. It will also be the cause for his sins to be expiated by Allāh, and his being granted forgiveness and Allāh shielding him from the people. It will likewise be the cause of him being a recipient of a great reward from
Allāh, as He – the Most High – said:
“O you who believe! Have taqwá (fear) of Allāh and believe in His Messenger; and He will bestow upon you a double portion of His mercy, and He will provide for you a light by which you will walk.””
Ibn Masʿūd (raḍī Allāhu ʿanhu) said:
“Indeed, I hold that a person forgets knowledge that which used to hold because of sins that he commits.” 
Wakīʿ Ibn al-Jarrāḥ (d.197H) – raḥimahullāh– said:
“I seek help in memorization by abandoning sin and disobedience.” 
Imām Mālik Ibn Anas (d.179H) – raḥimahullāh – said to al-Shāfiʿī (d.204H) – raḥimahullāh– when the two of them met:
“Indeed, I see that Allāh has placed a light upon your heart, so do not extinguish it with the darkness of disobedience and sin.” 
Imām Muḥammad Ibn Idrees al-Shāfiʿī said:
“Whosoever loves that Allāh should open-up his heart for him and grant light to him, then let him abandon speech about that which does not concern him, and abandon sins and turn away from disobedience. Then there will be between him and Allāh a hidden treasure of good actions. So if this is done, then Allāh will open up such knowledge for him, that will pre-occupy him. And indeed in death is the greatest pre-occupation.” 
Shaykh al-Islām Ibn Taymīyyah (d.728H) – raḥimahullāh– said:
“Allāh – the Most Perfect, the Most High – has made as a punishment for people’s sins, the absence of guidance and beneficial knowledge, as He says:
“They say: Our hearts are wrapped-up (and we do not understand). Rather, Allāh has put a seal upon their hearts because of their disbelief.” 
And He said:
“They say: Our hearts are wrapped-up (and we do not understand). Rather, Allāh has cursed them for their disbelief.” 
And He said:
“And We shall turn their hearts and their sight away from guidance, as they refused to believe therein for the first time.” 
And Allāh says:
“In their hearts is a disease and Allāh increases their disease.” 
And He says:
“So when they turned away, Allāh turned their hearts away.””
 Taken from an-Nubadh fī Aadaabit-Talabil-’Ilm (p. 12-15) of Shaykh Abū Anas.
 Sūrah al-Ḥadīd [57:28]
 Sūrah al-Anfāl [8:29]
 Sūrah al-Ḥadīd [57:28]
 Tafsīr Qurʾānul-’Adtheem (2/301-302) of Ibn Kathīr.
 Related by Wakīʿ in al-Zuhd (no. 329), and its isnād is ṣaḥīḥ.
 Related by Ibn Hibbān in Rawdatul-’Uqʿalá(p. 39)
 I’lāmul-Muwaqqi’een (4/258) of Ibn al-Qayyim.
 Related by al-Bayḥaqī in Manaaqibush-Shaafi’ee (2/171)
 Sūrah al-Nisāʾ [4:155]
 Sūrah al-Baqarah [2:88]
 Sūrah al-Anʿām [6:110]
 Sūrah al-Baqarah [2:10]
 Sūrah al-Ṣaff [61:5]
 Majmūʿ al-Fatāwá (14/152) of Shaykh al-Islām Ibn Taymīyyah.