waḥdahu lā sharīka lahu.
lahul-mulku wa lahul-ḥamdu
wa huwa `alā kulli shay'in qadīr.
Who has no partner.
His is the dominion and His is the praise,
and He is Able to do all things.
At-Tirmidhi. Al-Albani graded it good in Sahih At-Tirmidhi 3/184, and also Silsilatul-'Ahadith As-Sahihah 4/6.
Hisnul Muslim 237