The Essence
Al-Awwal is the First. There is absolutely nothing before Him. He is the origin of all existence and the cause of all things, while He Himself has no beginning.
In the Quran
هُوَ الْأَوَّلُ وَالْآخِرُ وَالظَّاهِرُ وَالْبَاطِنُ
"He is the First (Al-Awwal) and the Last, the Ascendant and the Intimate... (Surah Al-Hadid 57:3)"
In Your Duas
اللَّهُمَّ أَنْتَ الأَوَّلُ فَلَيْسَ قَبْلَكَ شَىْءٌ
"O Allah, You are the First, there is nothing before You."
— Sahih Muslim 2713