Then He says:

هُوَ الْحَيُّ لَا إِلَهَ إِلَّا هُوَ ...

He is the Ever Living, La ilaha illa Huwa;

means, He is the Ever Living, from eternity to eternity, Who was, is and shall be, the First and the Last, the Manifest, the Hidden.

لَا إِلَهَ إِلَّا هُوَ (La ilaha illa Huwa),

means, there is none comparable or equal to Him.

... فَادْعُوهُ مُخْلِصِينَ لَهُ الدِّينَ ...

so invoke Him making the religion for Him Alone.

means, affirm His Oneness by testifying that there is no God but He.

Imam Ahmad recorded that after ending every prayer, Abdullah bin Az-Zubayr used to say:

لَا إِلهَ إِلَّا اللهُ وَحْدَهُ لَا شَرِيكَ لَهُ،لَهُ الْمُلْكُ وَلَهُ الْحَمْدُ، وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيرٌ،

لَا حَوْلَ وَلَا قُوَّةَ إِلَّا بِاللهِ،

لَا إِلهَ إِلَّا اللهُ، وَلَا نَعْبُدُ إِلَّا إِيَّاهُ،

لَهُ النِّعْمَةُ وَلَهُ الْفَضْلُ وَلَهُ الثَّنَاءُ الْحَسَنُ،

لَا إِلهَ إِلَّا اللهُ مُخْلِصِينَ لَهُ الدِّينَ وَلَوْ كَرِهَ الْكَافِرُون

There is no (true) God except Allah Alone with no partner or associate, to Him belongs the dominion and praise, for He is able to do all things;

there is no strength and no power except with Allah;

there is no (true) God except Allah and we worship none but Him;

to Him belong blessings and virtue and goodly praise;

there is no (true) God except Allah, we worship Him in all sincerity even though the disbelievers may hate that.

He said,

"The Messenger of Allah used to say the Tahlil in this fashion after every prayer.''

Similar was also recorded by Muslim, Abu Dawud and An-Nasa'i.

... الْحَمْدُ لِلَّهِ رَبِّ الْعَالَمِينَ ﴿٦٥﴾

All the praises and thanks be to Allah, the Lord of all that exits.