[13].Surah Ar-Ra'd [The Thunder]: Ayat 27

Ayat 27. And those who disbelieve (in Prophethood of(Muhammad  [SAWW](PBUH) say: "Why is not a sign sent down to him (Muhammad  [SAWW](PBUH) from his Lord?" Say: "Verily, Allah sends astray whom He wills and guides unto Himself those who turn to Him in repentance." 

Hazrat Mu`awiyah (May Allah be pleased with him) reported: The Messenger of Allah  [SAWW](PBUH) said, "When Allah wishes good for someone, He bestows upon him the understanding of Deen.'' I am (The Messenger of Allah  [SAWW](PBUH) just a distributor, but the grant is from Allah. 

[Al-Bukhari Volume 01, Book 03, Hadith # 71]. 

Lesson : as mentioned above in Surah Ar-Ra'd Ayat 27. "Verily, Allah sends astray whom He wills and guides unto Himself those who turn to Him in repentance."

This Hadith makes the point, Knowledge and understanding of Deen (religion) here stands for the understanding of the Qur'an and Hadith, religious injunctions, and knowledge of the lawful and the unlawful. This Hadith highlights the excellence of knowledge and the fact that it is a sign of Allah's Help to the person who possesses it and acts upon it.