الْحَمْدُ لِلَّهِ رَبِّ الْعَالَمِينَ
All praises be to Allāh, the Lord of the worlds (for His perfect attributes and benevolent and just actions).
[Al-Fātiḥah, 1:2]

[Q]: Why is the understanding of “all praise” through the addition of the article (ال) added to the term “praise” (حمد) in the beginning of Sūrah al-Fātiḥah? Should we not simply understand it as it is precisely worded: ‘Praise be to Allāh, the Lord of the worlds.’

[A]: There is an underlying meaning in the addition of All of to “the praise” that is not achieved if someone were to merely utter ‘Praise be to Allāh’ without meaning ‘All of the praise.’ This addition to the word praise (ḥamd) is indicative of absolutely and entirely all praise and thanks being for Allāh [alone]. However, if we were to remove ‘all’ from the sentence, it would indicate simply the praise of the praiser himself being dedicated to Allāh, rather than all forms of praise.

As the literal meaning of the saying: ‘Praise be to Allāh’ is simply ‘I praise Allāh a great form of praise.’

This is not the [same] meaning as saying: ‘All praises be to Allāh, the Lord of the worlds ,’ as this [sūrah] is the Mother of the Qurʾān.

Rather, the complete interpretation of the phrase is as we have described; that all forms of praise are for Allāh, for He is the only One who Has the right to be worshipped [Oneness of Divinity], and [He is the only One who Has] bestowed bounties on His creation [Oneness of Lordship]. For His bounties are unparalleled, whether they be related to the religion or worldly life, the temporal or the everlasting.

Source: Tafsīr al-Ṭabarī 1:138-9
Translated by: Riyāḍ al-Kanadī