Narrated `Abdullah: I or somebody, asked Allah's Messenger (ﷺ) "Which is the biggest sin in the Sight of Allah?" He said, "That you set up a rival (in worship) to Allah though He Alone created you." I asked, "What is next?" He said, "Then, that you kill your son, being afraid that he may share your meals with you." I asked, "What is next?" He said, "That you commit illegal sexual intercourse with the wife of your neighbor." Then the following Verse was revealed to confirm the statement of Allah's Messenger: "Those who invoke not with Allah, any other god, nor kill life as Allah has forbidden except for just cause, nor commit illegal sexual intercourse." (25.68)
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا يَحْيَى، عَنْ سُفْيَانَ، قَالَ حَدَّثَنِي مَنْصُورٌ، وَسُلَيْمَانُ، عَنْ أَبِي وَائِلٍ، عَنْ أَبِي مَيْسَرَةَ، عَنْ عَبْدِ اللَّهِ،. قَالَ وَحَدَّثَنِي وَاصِلٌ، عَنْ أَبِي وَائِلٍ، عَنْ عَبْدِ اللَّهِ ـ رضى الله عنه ـ قَالَ سَأَلْتُ ـ أَوْ سُئِلَ رَسُولُ اللَّهِ صلى الله عليه وسلم ـ أَىُّ الذَّنْبِ عِنْدَ اللَّهِ أَكْبَرُ قَالَ " أَنْ تَجْعَلَ لِلَّهِ نِدًّا وَهْوَ خَلَقَكَ ". قُلْتُ ثُمَّ أَىٌّ قَالَ " ثُمَّ أَنْ تَقْتُلَ وَلَدَكَ خَشْيَةَ أَنْ يَطْعَمَ مَعَكَ". قُلْتُ ثُمَّ أَىٌّ قَالَ " أَنْ تُزَانِيَ بِحَلِيلَةِ جَارِكَ ". قَالَ وَنَزَلَتْ هَذِهِ الآيَةُ تَصْدِيقًا لِقَوْلِ رَسُولِ اللَّهِ صلى الله عليه وسلم {وَالَّذِينَ لاَ يَدْعُونَ مَعَ اللَّهِ إِلَهًا آخَرَ وَلاَ يَقْتُلُونَ النَّفْسَ الَّتِي حَرَّمَ اللَّهُ إِلاَّ بِالْحَقِّ وَلَا يَزْنُونَ}
sunnah.com