In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Shaikh Rabee Bin Haadi [may Allaah preserve him] said:
This [i.e. guarding one’s speech and deeds based on knowledge of the Qur’aan and Sunnah] is beneficial knowledge – praiseworthy knowledge – in the Sight of Allaah [The Blessed and Exalted]. The possessor of this knowledge is one regarded to be in a praiseworthy situation because when he utters statements, perform deeds and acts of worship, he pays close attention to the fact that Allaah [sees and hears him, and knows everything about him], and he does so sincerely for the Sake of Allaah. He worships Allaah as if he can see Allaah, but even though he cannot see Allaah [i.e. in this worldly life], he [firmly] believes that Allaah [The Blessed and Exalted] sees him, knows everything in his soul and heart, and knows everything he needs. He knows this because of his strong awareness -whilst engaged in worship and in all other affairs of his life- that Allaah [sees and hears him, and knows everything about him].
Knowledge is not merely about studying and obtaining certificates, rather the goal [or aim] is to acquire sound and precise understanding – sound understanding in affairs of Aqeedah, worship, good manners, good etiquettes and everything related to the life of a believer. It is obligated on the believers to carry out everything related to their lives based on the Book of Allaah and the [authentic] sunnah of Allaah’s Messenger [sallal laahu alayhi wasallam]. The believer performs acts of worship sincerely for the Sake of Allaah because Allaah commanded him [or her] to be sincere. [Allaah (The Blessed and Exalted) said]:
وَمَآ أُمِرُوٓاْ إِلَّا لِيَعۡبُدُواْ ٱللَّهَ مُخۡلِصِينَ لَهُ ٱلدِّينَ حُنَفَآءَ وَيُقِيمُواْ ٱلصَّلَوٰةَ وَيُؤۡتُواْ ٱلزَّكَوٰةَۚ وَذَٲلِكَ دِينُ ٱلۡقَيِّمَةِ
And they were commanded not, but that they should worship Allah, and worship none but Him Alone (abstaining from ascribing partners to Him), and perform As-Salat (Iqamat-as-Salat) and give Zakat: and that is the right religion. [Surah Al-Bayyinah’ Aayah 5]
[Source: Marhaban Yaa Taalibal Ilm’ pages 72 – 73. Slightly paraphrased]