It is narrated from Sayyiduna Mu'adh that the Prophet (peace and blessings be upon him) said: The one who laughs during prayer, the one who looks to the right and left, and the one who cracks his fingers are all on the same level.
Hadith Referenceمسند احمد / مسند المكيين / 15621
Hadith Gradingحکم دارالسلام:إسناده ضعيف مسلسل بالضعفاء