Sunan Ibn Majah, Volume 5, Book 33, Hadith 3824 (DarusSalam) ⓘ
It was narrated that Abu Musa said: "The Prophet (saas) heard me saying: 'La hawla wa la quwwata illa billah (there is no power and no strength except with Allah).' He said: 'O 'Abdullah bin Qais! Shall I not tell you of a word which is one of the treasures of Paradise?' I said: 'Yes, O Messenger of Allah.' He said: 'Say: La hawla wa la quwwata illa billah (There is no power and no strength except with Allah).'"
حَدَّثَنَا مُحَمَّدُ بْنُ الصَّبَّاحِ، أَنْبَأَنَا جَرِيرٌ، عَنْ عَاصِمٍ الأَحْوَلِ، عَنْ أَبِي عُثْمَانَ، عَنْ أَبِي مُوسَى، قَالَ سَمِعَنِي النَّبِيُّ ـ صلى الله عليه وسلم ـ وَأَنَا أَقُولُ، لاَ حَوْلَ وَلاَ قُوَّةَ إِلاَّ بِاللَّهِ . قَالَ " يَا عَبْدَ اللَّهِ بْنَ قَيْسٍ أَلاَ أَدُلُّكَ عَلَى كَلِمَةٍ مِنْ كُنُوزِ الْجَنَّةِ " . قُلْتُ بَلَى يَا رَسُولَ اللَّهِ . قَالَ " قُلْ لاَ حَوْلَ وَلاَ قُوَّةَ إِلاَّ بِاللَّهِ " .
also referenced under: Hadith 3824 (Reference) & Book 33, Hadith 169 (In-Book)