ʿUyūn akhbār al-Riḍā
Hadith 9595 - وَبِهذَا الإِسنادِ قالَ: قالَ رَسُولُ اللَّهِ صَلَّى اللهُعَلَيْهِ وَآلِهِ: الدُّعاءُ سِلاحُ المُؤمِنِ، وَعِمادُ الدِّينِ، وَنُورُ السَّمواتِ وَالأَرْضِ[فَعَلَيكُم بِالدُّعاءِ وَاخلِصُوا النِّيَّةَ] .
31-95 According to the same documentation, God’s Prophet (S) said, “Supplication is the weapon of a believer. It is the pillar of the religion, light from the heavens and the Earth. (Thus I advise you to say supplications and purify your intentions.)”