Al-Kāfi - Volume 2 > Speaking of Allah, the Majestic, the Glorious, Secretly
Hadith #2

2ـ عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ خَالِدٍ عَنْ إِسْمَاعِيلَ بْنِ مِهْرَانَ عَنْ سَيْفِ بْنِ عَمِيرَةَ عَنْ سُلَيْمَانَ بْنِ عَمْرٍو عَنْ أَبِي الْمَغْرَاءِ الْخَصَّافِ رَفَعَهُ قَالَ قَالَ أَمِيرُ الْمُؤْمِنِينَ (عَلَيهِ السَّلام) مَنْ ذَكَرَ الله عَزَّ وَجَلَّ فِي السِّرِّ فَقَدْ ذَكَرَ الله كَثِيراً إِنَّ الْمُنَافِقِينَ كَانُوا يَذْكُرُونَ الله عَلانِيَةً وَلا يَذْكُرُونَهُ فِي السِّرِّ فَقَالَ الله عَزَّ وَجَلَّ يُراؤُنَ النَّاسَ وَلا يَذْكُرُونَ الله إِلا قَلِيلاً.

2. A number of our people have narrated from Ahmad ibn Muhammad ibn Khalid from Isma’Il ibn Mehran from Sayf ibn ‘Amirah from Sulayman ibn ‘Amr from abu al-Maghra’ al-Khassaf in a marfu’ manner from Amir al-Mu’minin, Ali ibn abu Talib (a.s.) who has said the following: “Whoever speaks of Allah, the Most Majestic, the Most Holy, secretly, has spoken of Allah very often. The hypocrites speak of Allah in public but they do not speak of Him in secret to which Allah, the Most Majestic, the Most Holy, has said, ‘They stand up in prayer lazily just to show that they pray, but, in truth they speak of Allah very little.’” (4:142)