Hadithcore
Mishkat al-Masabih, 579

‘Abdallah b. Shaqiq said that the companions of God’s Messenger did not consider the abandonment of any good deeds but prayer to be infidelity. Tirmidhi transmitted it.

وَعَن عبد الله بن شَقِيق قَالَ: كَانَ أَصْحَابُ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَا يَرَوْنَ شَيْئًا مِنَ الْأَعْمَالِ تَركه كفر غير الصَّلَاة. رَوَاهُ التِّرْمِذِيّ

References1 variant
In-Book Reference
Book 4, Hadith 15