When the death of Abu Talib approached, Messenger of Allah ﷺ came to him and said, "Say: La ilaha illallah, a word with which I will be able to defend you before Allah."  

لَمَّا حَضَرَتْ أَبَا طَالِبٍ الْوَفَاةُ جَاءَهُ رَسُولُ اللَّهِ ﷺ فَقَالَ قُلْ لاَ إِلَهَ إِلاَّ اللَّهُ كَلِمَةً أُحَاجُّ لَكَ بِهَا عِنْدَ اللَّهِ  

Messenger of Allah ﷺ said, "(The following are) two words (sentences or utterances) that are very easy for the tongue to say, and very heavy in the balance (of reward), and most beloved to the Gracious Almighty (And they are): Subhan Allahi wa bi-hamdihi; Subhan Allahi-l-'Adhim,"  

قَالَ رَسُولُ اللَّهِ ﷺ كَلِمَتَانِ خَفِيفَتَانِ عَلَى اللِّسَانِ ثَقِيلَتَانِ فِي الْمِيزَانِ حَبِيبَتَانِ إِلَى الرَّحْمَنِ سُبْحَانَ اللَّهِ وَبِحَمْدِهِ سُبْحَانَ اللَّهِ الْعَظِيمِ  

Messenger of Allah ﷺ said a sentence and I said another. He said, "Whoever dies while he is setting up rivals along with Allah (i.e. worshipping others along with Allah) shall be admitted into the (Hell) Fire." And I said the other: "Whoever dies while he is not setting up rivals along with Allah (i.e. worshipping none except Allah) shall be admitted into Paradise."  

قَالَ رَسُولُ اللَّهِ ﷺ كَلِمَةً وَقُلْتُ أُخْرَى مَنْ مَاتَ يَجْعَلُ لِلَّهِ نِدًّا أُدْخِلَ النَّارَ وَقُلْتُ أُخْرَى مَنْ مَاتَ لاَ يَجْعَلُ لِلَّهِ نِدًّا أُدْخِلَ الْجَنَّةَ