Basics- Revising and Revisiting The Most Important Fundamentals: [Al-Ikhlaas (Sincerity) Is The Third Condition of The Shahaadah]
In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
The third condition of the Shahaadah [Laa ilaaha illal laah- There is no deity worthy of worship except Allaah] is Al-Ikhlaas [Sincerity] which necessitates a negation of Shirk [ascribing partners with Allaah in worship or devoting acts of worship to Allaah and others besides Allaah] and Riyaa (ref a) [to perform acts of worship only to be seen, praised etc].
Allaah [The Exalted] said: [وَمَآ أُمِرُوٓاْ إِلَّا لِيَعۡبُدُواْ ٱللَّهَ مُخۡلِصِينَ لَهُ ٱلدِّينَ – And they were commanded except to devote all the religion sincerely to Allaah (by abstaining from ascribing partners to Him)]. [Surah Al-Bayyinah 5]
Abu Hurairah [may Allaah be pleased with him] said that the Prophet [peace and blessings of Allaah be upon him] said, “The happiest person who will receive my intercession on the day of judgement is the one who says [Laa ilaaha illal laah- There is no deity worthy of worship except Allaah [ خالصا من قلبه – purely from his (or her) heart] will enter paradise”. [Al-Bukhaari 99]
So, the Prophet [peace and blessings of Allaah be upon him] made it a condition that the Shahaadah must he accompanied with sincerity and that a person devotes acts of worship only to Allaah. Ponder upon the meaning of the word خالص in the Arabic language in the statement of Allaah [The Exalted]: وَإِنَّ لَكُمۡ فِى ٱلۡأَنۡعَـٰمِ لَعِبۡرَةً۬ۖ نُّسۡقِيكُم مِّمَّا فِى بُطُونِهِۦ مِنۢ بَيۡنِ فَرۡثٍ۬ وَدَمٍ۬ لَّبَنًا خَالِصً۬ا سَآٮِٕغً۬ا لِّلشَّـٰرِبِينَ – And verily! In the cattle, there is a lesson for you. We give you to drink of that which is in their bellies, from between excretions and blood, (لَّبَنًا خَالِصً۬ا – pure milk); palatable to the drinkers]. [Surah An-Nahl. 66]
[Khaalisan – خالصا]: meaning, pure, unadulterated, no other mixtures in it- neither blood nor excretions. Even though this milk exited between excretions and blood, it comes out completely pure and unadulterated. So, sincerity in worship to Allaah necessitates that worship is pure and unadulterated – devoted only to Allaah; but if devoted to Allaah and others, it is removed from this state of purity and will not be accepted by Allaah. This is why Allaah stated in the Hadeeth Al-Qudsee (ref b), “I am free from having any partner, so whoever performs an act of worship and associates others as partners with me (in it), I will reject the deed and the doer”. (ref c)
An Excerpt From: Explanation of Important Lessons For The Muslim Ummah. page 49. Maktabah Malik Al-Fahad 1436AH. (2015)]
Ref a: Types of Riyaa: Read here: https://www.abukhadeejah.com/minor-and-major-hypocrisy-and-the-hypocrites-by-al-barbahaaree-explanation-of-al-fawzaan/
Ref b: What is Hadeeth Qudsee? Shaikh Abdul Waahid Abu Khadeejah [may Allaah preserve him] stated: “Some of the sayings are known as “Hadīth Qudsee”. These are Allāh’s words revealed to Muhammad (peace and blessings be upon him) that are not a part of the Qur’an. The difference between Prophetic Hadith and Hadith Qudsee is that the Prophetic Hadīth are the intent of Allah expressed in Muhammad’s words. The Hadith Qudsee are the Words of Allah directly stated upon the tongue of the Prophet Muhammad (peace and blessings be upon him). Example: Abu Hurairah said that the Prophet (peace and blessings be upon him) said that Allāh said: “Spend in charity, O son of Adam! And I will spend on you.” It was collected by Bukhāree. The Hadith have as much authority as the Qur’an as shown in these verses: “Obey Allah and obey the Messenger,” and, “Whatever the Messenger gives you take it, and whatever he forbids for you, abstain from it”. https://www.abukhadeejah.com/the-hadith-and-the-sunnah-islam-1-7/
Ref c: Sharh Usool Al-Eemaan. page 27. By Shaikh Saaleh Aalah Ash-Shaikh [may Allaah preserve him]. 1st Edition. Publisher: Daar Al-Aasimah 1431AH (2010)