The Recitation of these Surahs in the Optional Prayers
It has been confirmed in Sahih Muslim from Jabir that the Messenger of Allah recited this Surah (Al-Kafirun) and قُلْ هُوَ اللَّهُ أَحَدٌ (Say: "He is Allah One.'' (Surah: 112)), in the two Rakahs of Tawaf.
It is also recorded in Sahih Muslim in a Hadith of Abu Hurayrah that the Messenger of Allah recited these two Surahs in the two Rakahs (optional prayer) of the Morning prayer.
Imam Ahmad recorded from Ibn Umar that the Messenger of Allah recited in the two Rakahs before the Morning prayer and the two Rakahs after the Sunset prayer on approximately ten or twenty different occasions, قُلْ يَا أَيُّهَا الْكَافِرُونَ(Say: "O Al-Kafirun!'') and قُلْ هُوَ اللَّهُ أَحَدٌ (Say: " He is Allah One.'' (Surah: 112)).
Ahmad also recorded that Ibn Umar said,
"I watched the Prophet twenty-four or twenty-five times reciting in the two Rakahs before the Morning prayer and the two Rakahs after the Sunset prayer, قُلْ يَا أَيُّهَا الْكَافِرُونَ(Say: "O Al-Kafirun!'') and قُلْ هُوَ اللَّهُ أَحَدٌٌ (Say: "He is Allah One.'') (Surah: 112))."
Ahmad recorded that Ibn `Umar said,
"I watched the Prophet for a month and he would recite in the two Rakahs before the Morning prayer, قُلْ يَا أَيُّهَا الْكَافِرُونَ (Say: "O Al-Kafirun!'') and قُلْ هُوَ اللَّهُ أَحَدٌ (Say: " He is Allah One.'' (Surah: 112)).
This was also recorded by At-Tirmidhi, Ibn Majah and An-Nasa'i.
At-Tirmidhi said, "Hasan.''
It has already been mentioned previously in a Hadith that it (Surah Al-Kafirun) is equivalent to a fourth of the Qur'an and Az-Zalzalah is equivalent to a fourth of the Qur'an.
The Declaration of Innocence from Shirk
This Surah is the Surah of disavowal (renunciation) from the deeds of the idolators. It commands a complete disavowal of that.
قُلْ يَا أَيُّهَا الْكَافِرُونَ ﴿١﴾
Say: O disbelievers!
includes every disbeliever on the face of the earth, however, this statement is particularly directed towards the disbelievers of the Quraysh.
It has been said that in their ignorance they invited the Messenger of Allah to worship their idols for a year and they would (in turn) worship his God for a year. Therefore, Allah revealed this Surah and in it
He commanded His Messenger to disavow himself from their religion completely
لَا أَعْبُدُ مَا تَعْبُدُونَ ﴿٢﴾
I worship not that which you worship.
meaning, statues and rival gods.
وَلَا أَنتُمْ عَابِدُونَ مَا أَعْبُدُ ﴿٣﴾
Nor will you worship whom I worship.
and He is Allah Alone, Who has no partner. So the word Ma (what) here means Man (who).
Then Allah says,
وَلَا أَنَا عَابِدٌ مَّا عَبَدتُّمْ ﴿٤﴾
وَلَا أَنْتُمْ عَابِدُونَ مَا أَعْبُدُ ﴿٥﴾
And I shall not worship that which you are worshipping.
Nor will you worship whom I worship.
meaning, `I do not worship according to your worship, which means that I do not go along with it or follow it. I only worship Allah in the manner in which He loves and is pleased with.'
Thus, Allah says, وَلَا أَنَا عَابِدٌ مَّا عَبَدتُّمْ (Nor will you worship whom I worship.)
meaning, `you do not follow the commands of Allah and His Legislation in His worship. Rather, you have invented something out of the promptings of your own souls.'
This is as Allah says,
إِن يَتَّبِعُونَ إِلاَّ الظَّنَّ وَمَا تَهْوَى الاٌّنفُسُ وَلَقَدْ جَآءَهُم مِّن رَّبِّهِمُ الْهُدَى
They follow but a guess and that which they themselves desire, whereas there has surely come to them the guidance from their Lord! (53:23)
Therefore, the disavowal is from all of what they are involved. For certainly the worshipper must have a god whom he worships and set acts of worship that he follows to get to him. So the Messenger and his followers worship Allah according to what He has legislated. This is why the statement of Islam is
"There is no God worthy of being worshipped except Allah, and Muhammad is the Messenger of Allah.''
This means that there is no (true) object of worship except Allah and there is no path to Him (i.e., way of worshipping Him) other than that which the Messenger came with.
The idolaters worship other than Allah, with acts of worship that Allah has not allowed. This is why the Messenger said to them,
لَكُمْ دِينُكُمْ وَلِيَ دِينِ ﴿٦﴾
To you be your religion, and to me my religion.
This is similar to Allah's statement,
وَإِن كَذَّبُوكَ فَقُل لِّى عَمَلِى وَلَكُمْ عَمَلُكُمْ أَنتُمْ بَرِيئُونَ مِمَّآ أَعْمَلُ وَأَنَاْ بَرِىءٌ مِّمَّا تَعْمَلُونَ
And if they belie you, say:
"For me are my deeds and for you are your deeds! You are innocent of what I do, and I am innocent of what you do!'' (10:41)
and He said,
لَنَآ أَعْمَـلُنَا وَلَكُمْ أَعْمَـلُكُمْ
To us our deeds, and to you your deeds. (28:55)
"It has been said,
لَكُمْ دِينَكُمْ (To you be your religion.) means disbelief.
وَلِيَ دِينِ(and to me my religion.) means, Islam.
This is the end of the Tafsir of Surah Al-Kafirun, and all praise and blessings are due to Allah.