A/alaikum, my question is regarding the zikr: LA ILAHA ILLAHU, WAHDAHU LA SHARIKA LAHU, LAHUL MULKU WA LAHUL HAMDU, WA HUWA 'ALA KULLI SHAY'IN QADIR. Is the phrase YUHYI WA YU MITU before ...WA HUWA ALA KULLI SHAY'IN QADIR authentic. Ma'assalam,

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

This phrase ‘Yuhyi Wa Yumeet’ (He gives life and causes death) is confirmed from the Prophet in some forms of the mention of Allaah, like the mention of Allaah after Tasleem (i.e. saying Salaam when concluding the prayer). At-Tirmithi reported that the Prophet used to say after Tasleem: "Laa 'Ilaaha 'Illa Allaahu Wahdahu La Shareeka Lahu, Lahul Mulku Wa Lahul Hamdu Yuhyi Wa Yumeet Wahuwa A'la Kulli Shay'iin Qadeer. Allahumma La Maani’a Lima A’tayta, Wa Laa Mu’itiya Lima Man’ata, Wala Yanfa’u Thal Jaddi Minkal Jaddu." ‘None has the right to be worshipped except Allaah, alone, without partner, to Him belong all sovereignty and praise, He gives life and causes death and He is over all things Omnipotent. O Allaah, none can withhold what You have bestowed and none can bestow what You have withheld, and the greatness of the great will be no avail to him against You.’

Also, At-Tirmithi reported this supplication when entering the market: "Laa 'Ilaaha 'Illa Allaahu Wahdahu La Shareeka Lahu, Lahul Mulku Wa Lahul Hamdu Yuhyi wa Yumeet Wa Huwa Hayyun laa Yamoot Biyadihi Al-Khayru Wahuwa A'la Kulli Shay'iin Qadeer. None has the right to be worshipped except Allaah, Alone, without partner, to Him belongs all sovereignty and praise. He gives life and causes death, and He is ever living and does not die. In His hand is all good and He is over all things Omnipotent.’

Besides, this phrase is also reported in the mention after the Maghrib and Fajr prayers in Musnad Ahmad: “Whoever says before leaving and before moving from his place and unfolding his leg (i.e. before changing his sitting position in Tashahhud): 'Laa 'Ilaaha 'Illa Allaahu Wahdahu La Shareeka Lahu, Lahul Mulku Wa Lahul Hamdu Biyadihi Al-Khayru Yuhyi Wa Yumeet Wahuwa A'la Kulli Shay'iin Qadeer. None has the right to be worshipped except Allaah, Alone, without partner, to Him belongs all sovereignty and praise. In His hand is all good, He gives life and causes death, and He is over all things Omnipotent.’ Ten times, for each one ten good deeds will be written for him, and ten bad deeds will be wiped out from him, and he will be elevated ten degrees, and it will be a protection from every misfortune and a protection from the outcast (cursed) devil…”

Allaah Knows best.