Allah سبحانه وتعالى says in a verse of Surah Furqan:
أَرَأَيْتَ مَنِ اتَّخَذَ إِلَهَهُ هَوَاهُ أَفَأَنتَ تَكُونُ عَلَيْهِ وَكِيلًا
Have you not seen he who has made his nafs god? [N.B. Partial translation]
[Surah al Furqan 25:43]
In a hadeeth Sayyidina Shaddad ibn Aws رضى الله عنه narrated that the Prophet صلى الله عليه وسلم said:
عَنْ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ الْكَيِّسُ مَنْ دَانَ نَفْسَهُ وَعَمِلَ لِمَا بَعْدَ الْمَوْتِ
وَالْعَاجِزُ مَنْ أَتْبَعَ نَفْسَهُ هَوَاهَا وَتَمَنَّى عَلَى اللَّهِ
The intelligent one is he who suppresses his desires (nafs) and who works for the hereafter, and the helpless one is he who follows his desires and hopes for the mercy of Allah.
[Reported by Tirmidhi, ibn Majah and Ahmed]
The reason why Banu Israeel rejected the ambiya عليهم السلام is because they worshipped their whims and desires (nafs). Following ones nafs leads one to reject the truth and therefore one must work hard to overcome the nafs.
We live in a time when people have formed their own ideas of piety and deen, good and bad according to their own desires . Everyone wants deen to be that what their nafs want it to be and not what Allah سبحانه وتعالى wants it to be. Thus, everyone has their own idea of religion (designer spirituality); every person has his or her own Islam according to their nafs. Any part of deen which does not agree with their own nafs is immediately rejected and eventually, such a person ends up worshipping their own nafs rather than Allah سبحانه وتعالى.
We must make our inner self and nature conform to deen rather than the other way around. Shaitaan has fooled us into having our idea of piety and spirituality. We must sacrifice our own desire and follow the laws of Allah سبحانه وتعالى. This is true sacrifice.
Any action should only be for the pleasure of Allah سبحانه وتعالى and not in order to satisfy our desires or for name and fame.
[This excerpt is based on a brothers’ majlis (gathering for spiritual training) held by Shaykh Abu Yusuf Riyadh ul Haq on 9th April 1997 and 7th May 1997].