The smallest amount that gets a person out
It is measured three times, and it keeps getting smaller.
لاَ إِلَهَ إِلاَّ اللَّهُ، وَفِي قَلْبِهِ وَزْنُ شَعِيرَةٍ مِنْ خَيْرٍ
Lā ilāha illā-Llāh, wa fī qalbihi waznu shaʿīratin min khayr
“There is no god but Allah, and in his heart is the weight of a grain of barley of good.”
Where this comes from
It is given three times over, and the measure drops each time. A grain of barley. Then a grain of wheat. Then an atom's weight. Every version ends the same way, with the person coming out.
The full narration
Narrated Anas: The Prophet (ﷺ) said, "Whoever said "None has the right to be worshipped but Allah and has in his heart good (faith) equal to the weight of a barley grain will be taken out of Hell. And whoever said: "None has the right to be worshipped but Allah and has in his heart good (faith) equal to the weight of a wheat grain will be taken out of Hell. And whoever said, "None has the right to be worshipped but Allah and has in his heart good (faith) equal to the weight of an atom will be taken out of Hell
Source
Ṣaḥīḥ al-Bukhārī · 44
- Agreed upon as authentic (al-Bukhārī / Muslim)