Al-Kāfi

Hadith 1621
dua
7ـ عَنْهُ عَنْ أَبِيهِ عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ عَبْدِ الله بْنِ سِنَانٍ عَنْ أَبِي عَبْدِ الله (عَلَيهِ السَّلام) قَالَ الدُّعَاءُ أَنْفَذُ مِنَ السِّنَانِ الْحَدِيدِ.
7. It is narrated from him (narrator of the Hadith above) from his father from Ibn Abi ‘Umayr from ‘Abd Allah ibn Sinan from Abu ‘Abdillah (a.s.) who has said the following: “Abu ‘Abd Allah (a.s.) has said, ‘Prayer, pleading before Allah for help, is more effective than spears of iron.’”
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī