Abu Huraira reported: The Prophet, peace and blessings be upon him, said, “The most truthful word ever spoken by an Arab poet is the saying of Labid: Everything besides Allah is in vain.”
Source: Ṣaḥīḥ Muslim 2256
Grade: Sahih (authentic) according to Muslim
عَنْ أَبِي هُرَيْرَةَ عَنْ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ أَشْعَرُ كَلِمَةٍ تَكَلَّمَتْ بِهَا الْعَرَبُ كَلِمَةُ لَبِيدٍ أَلَا كُلُّ شَيْءٍ مَا خَلَا اللَّهَ بَاطِلٌ
2256 صحيح مسلم كتاب الشعر