Al-Kāfi - Volume 1 > Chapter On Attribute Of Essence (Sifat al-DhDhat) Of Allah
Hadith #3

3ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ مُحَمَّدِ بْنِ الْحُسَيْنِ عَنْ صَفْوَانَ بْنِ يَحْيَى عَنِ الْكَاهِلِيِّ قَالَ كَتَبْتُ إِلَى أَبِي الْحَسَنِ (عَلَيْهِ السَّلام) فِي دُعَاءٍ الْحَمْدُ لله مُنْتَهَى عِلْمِهِ فَكَتَبَ إِلَيَّ لا تَقُولَنَّ مُنْتَهَى عِلْمِهِ فَلَيْسَ لِعِلْمِهِ مُنْتَهًى وَلَكِنْ قُلْ مُنْتَهَى رِضَاهُ‏.

3. Muhammad ibn Yahya has narrated from Muhammad ibn al-Husayn from Safwan ibn Yahya from al-Kahili who has said the following. “I wrote to abu al-Hassan (al-Kazim) (a.s.), praising Allah in my letter as, ‘All praise belongs to Allah to the limit of His knowledge.’” He wrote back to me, “Do not say, “To the limit of His knowledge because there is no limit to His knowledge. Instead say, “All praise belongs to Allah to the limit of His pleasure.”