In The Name of Allaah, The Most Merciful, The Bestower of Mercy.

Abdullah Ibn Umar [may Allaah be pleased with him and his father] said, “I have not rejoiced with anything in Islam more than the joy that none of these desires (i.e. religious innovations) have entered my heart”. (1)

Imaam Al-Bukhaari [may Allaah have mercy upon him] said, “Chapter: Learning about the Laws of Inheritance. Uqbah Bin Aamir said, ‘Learn (the laws of Inheritance) before those who depend on Az-Zan (guessing), namely, those who base their judgment on mere presumption'”. (2)

Imaam An-Nawawi [may Allaah have mercy upon him] said, “The meaning of this is that you should learn from those who possess true precision, expertise and fear of Allaah before they go away (through death) and then there appears a people who speak about knowledge in conformity with the desires of their souls and with presumptions, which have no (clear or unambiguous) proof in the Islamic legislation”. (3)

Abul Aaliyah [may Allaah have mercy upon him] said, “Learn Islam and do not turn away from when you learn. It is obligated on you to adhere to the straight path because indeed it is Islaam. Do not you deviate from Islam -neither to the right nor the left. It is obligated on you to adhere to the Sunnah of your Prophet and the path his companions, and beware of these desires (i.e. religious innovations) that bring about enmity and hatred between the people”. (4)

Shaikhul Islaam Ibn Taymiyyah [may Allaah have mercy upon him] said, “The human being has that tendency to incline towards injustice and ignorance, and the initial affair regarding him is that he does not possess knowledge and his inclination is towards the evil he desires; therefore, he constantly in need of detailed (unambiguous) knowledge by way of which his ignorance ceases and to be just in his love, hatred, pleasure, anger, actions, abandonment, when he gives, witholds, eats, drinks, sleep and wakes up. He is in need of knowledge to put a stop to his ignorance in everything he says and justice to put a stop to his injustice. And unless Allaah grants him detail knowledge and (detail knowledge regarding the precepts of) of justice, there would be that ignorance and injustice in him that would exit him from the straight path”. (5)

Shaikhul Islaam [may Allaah have mercy upon him] also said, “It is well known that the (act) of shunning by those who (express their) aversion or the love of those who are in agreement is neither an indication of the correctness nor corruption of a statement, except when it is based on guidance from Allaah; rather merely (utilising) a statement as proof (without guidance from Allaah) is tantamount to following desires. Allaah [The Most High] said: [ وَإِنَّ كَثِيرً۬ا لَّيُضِلُّونَ بِأَهۡوَآٮِٕهِم بِغَيۡرِ عِلۡمٍ‌ۗ – And surely many do lead (mankind) astray by their own desires through lack of knowledge]. [Surah Al-An’aam. Verse 119]

Allaah [The Most High] said:

[ فَإِن لَّمۡ يَسۡتَجِيبُواْ لَكَ فَٱعۡلَمۡ أَنَّمَا يَتَّبِعُونَ أَهۡوَآءَهُمۡ‌ۚ وَمَنۡ أَضَلُّ مِمَّنِ ٱتَّبَعَ هَوَٮٰهُ بِغَيۡرِ هُدً۬ى مِّنَ ٱللَّهِ‌ۚ – But if they answer you not (i.e. do not believe in your doctrine of Islamic Monotheism, nor follow you), then know that they only follow their own lusts. And who is more astray than one who follows his own lusts, without guidance from Allah?] [Surah Al-Qasas. Verse 50]

And Allaah [The Most High] said to Dawud [peace be upon him]: [وَلَا تَتَّبِعِ ٱلۡهَوَىٰ فَيُضِلَّكَ عَن سَبِيلِ ٱللَّهِ‌ۚ – And follow not your desire for it will mislead you from the Path of Allah]. [Surah Saad. Verse 26]

Allaah [The Most High] said:

[ فَإِن شَهِدُواْ فَلاَ تَشْهَدْ مَعَهُمْ وَلاَ تَتَّبِعْ أَهْوَاء الَّذِينَ كَذَّبُواْ بِآيَاتِنَا وَالَّذِينَ لاَ يُؤْمِنُونَ بِالآخِرَةِ وَهُم بِرَبِّهِمْ يَعْدِلُونَ – Then if they testify, testify not you (O Muhammad) with them. And you should not follow the vain desires of such as treat Our Ayat (proofs, evidences, verses, lessons, signs, revelations, etc.) as falsehoods, and such as believe not in the Hereafter, and they hold others as equal (in worship) with their Lord]. [Surah Al-An’aam. Verse 150]
Allaah [The Most High] said:

قُلۡ يَـٰٓأَهۡلَ ٱلۡڪِتَـٰبِ لَا تَغۡلُواْ فِى دِينِڪُمۡ غَيۡرَ ٱلۡحَقِّ وَلَا تَتَّبِعُوٓاْ أَهۡوَآءَ قَوۡمٍ۬ قَدۡ ضَلُّواْ مِن قَبۡلُ وَأَضَلُّواْ ڪَثِيرً۬ا وَضَلُّواْ عَن سَوَآءِ ٱلسَّبِيلِ

Say (O Muhammad): “O people of the Scripture (Jews and Christians)! Exceed not the limits in your religion (by believing in something) other than the truth, and do not follow the vain desires of people who went astray in times gone by, and who misled many, and strayed (themselves) from the Right Path)”. [Surah Al-Maa’idah. Verse 77]

So whoever follows the desires of the people after (clarification of) the knowledge Allaah has revealed to His Messenger and the guidance He clarified for His slaves, then he (i.e. such a person) has a resemblance (to those regarded as followers of desires). And due to this, the proponents of religious innovations and factionalism – those who oppose the Qur’aan and authentic Prophetic path – were named Ahlul Ahwaa [the people of desires] by the pious predecessors, because of the fact that they accept what they love and reject what they hate based on their desires without guidance from Allaah. (6)

Al-Allaamah Rabee Bin Haadi Al-Mad’khali [may Allaah preserve him] said:

Allaah [Glorified and Exalted be He] warned against Ahlul Bidah and clarified for us that they are people of desires, and that they follow Mutashaabihaat [i.e. texts that are not entirely clear in what they indicate, so they are referred back to other texts to be explained] and they abandon the Muhkamaat [i.e. texts that are very clear]. Aa’isha [may Allaah be pleased with him] said: The Messenger [peace and blessings of Allaah be upon him] recited this ayah:

هُوَ الَّذِي أَنزَلَ عَلَيْكَ الْكِتَابَ مِنْهُ آيَاتٌ مُّحْكَمَاتٌ هُنَّ أُمُّ الْكِتَابِ وَأُخَرُ مُتَشَابِهَاتٌ ۖ فَأَمَّا الَّذِينَ فِي قُلُوبِهِمْ زَيْغٌ فَيَتَّبِعُونَ مَا تَشَابَهَ مِنْهُ ابْتِغَاءَ الْفِتْنَةِ وَابْتِغَاءَ تَأْوِيلِهِ ۗ وَمَا يَعْلَمُ تَأْوِيلَهُ إِلَّا اللَّهُ ۗ وَالرَّاسِخُونَ فِي الْعِلْمِ يَقُولُونَ آمَنَّا بِهِ كُلٌّ مِّنْ عِندِ رَبِّنَا ۗ وَمَا يَذَّكَّرُ إِلَّا أُولُو الْأَلْبَابِ

It is He Who has sent down to you [Muhammad] the Book [this Qur’an]. In it are Verses that are (entirely clear, they are the foundations of the Book [and those are the Verses of Al-Ahkaam (commandments, etc.), Al-Faraa’id (obligatory duties) and Al-Hudood (legal laws for the punishment of thieves, adulterers, etc.)]; and others are Mutashaabihaat (i.e. not entirely clear in what they indicate, so they are to be referred back to the Muhkamaat to be explained]. So, as for those in whose hearts there is a deviation (from the truth) they follow that which is not entirely clear thereof, seeking Al-Fitnah (polytheism and trials, etc.), and seeking for its hidden meanings, but none knows its hidden meanings except Allaah. And those who are firmly grounded in knowledge say: ‘’We believe in it; the whole of it (clear and unclear Verses) are from our Lord.” And none receive admonition except men of understanding.’’ [Surah Aal Imraan. Aayah 7]  [Then] she [i.e. Aa’isha] said: The Messenger said, ‘’If you see those who follow thereof that is not entirely clear, then they are those whom Allah has named [as having deviation (from the truth)] so beware of them’’. [Bukhaari Number 4547]

Allaah clarified that they [i.e. ahlul bidah] have desires [i.e. evil desires] and deviation with them, and that they intend to misguide themselves and other people! (7)

[Ref 1: Sharh Usool Al-Ittiqaad Ahlis Sunnah Wal Jamaa’ah. 1/130]
[Ref 2: Saheeh Al-Bukhaari. Book of Al-Fara’id (The Laws of Inheritance). Chapter heading of Hadeeth 6724]
[Ref 3: Al-Majmoo 1/42]
[Ref 4: Iqtidaa As-Siraat Al-Mustaqeem 1/97]
[Ref 5: Majmoo Al-Fataawaa 14/27]
[Ref 6: An Excerpt from Majmoo Al-Fataawaa 4/189-190. slightly paraphrased]

[Ref 7: Sharh Aqeedah As-Salaf Ashaab Al-Hadeeth’ pages 301-304′. slightly paraphrased]