The Meaning of Al-Hamd
Abu Ja`far bin Jarir said, "The meaning of (Al-Hamdu Lillah) (all praise and thanks be to Allah) is: all thanks are due purely to Allah, alone, not any of the objects that are being worshipped instead of Him, nor any of His creation. These thanks are due to Allah's innumerable favors and bounties, that only He knows the amount of. Allah's bounties include creating the tools that help the creation worship Him, the physical bodies with which they are able to implement His commands, the sustenance that He provides them in this life, and the comfortable life He has granted them, without anything or anyone compelling Him to do so. Allah also warned His creation and alerted them about the means and methods with which they can earn eternal dwelling in the residence of everlasting happiness. All thanks and praise are due to Allah for these favors from beginning to end.''
Further, Ibn Jarir commented on the Ayah,
(Al-Hamdu Lillah), that it means, "A praise that Allah praised Himself with, indicating to His servants that they too should praise Him, as if Allah had said, `Say: All thanks and praise is due to Allah.' It was said that the statement,
(All praise and thanks be to Allah), entails praising Allah by mentioning His most beautiful Names and most honorable Attributes. When one proclaims, `All thanks are due to Allah,' he will be thanking Him for His favors and bounties.''
The Difference between Praise and Thanks
Hamd is more general, in that it is a statement of praise for one's characteristics, or for what he has done. Thanks are given for what was done, not merely for characteristics.
The Statements of the Salaf about Al-Hamd
Hafs mentioned that `Umar said to `Ali, "We know La ilaha illallah, Subhan Allah and Allahu Akbar. What about Al-Hamdu Lillah'' `Ali said, "A statement that Allah liked for Himself, was pleased with for Himself and He likes that it be repeated.'' Also, Ibn `Abbas said, "Al-Hamdu Lillah is the statement of appreciation. When the servant says Al-Hamdu Lillah, Allah says, `My servant has praised Me.'' Ibn Abi Hatim recorded this Hadith.
The Virtues of Al-Hamd
Imam Ahmad bin Hanbal recorded that Al-Aswad bin Sari` said, "I said, `O Messenger of Allah! Should I recite to you words of praise for My Lord, the Exalted, that I have collected' He said,
(Verily, your Lord likes Al-Hamd.)''
An-Nasa'i also recorded this Hadith. Furthermore, Abu `Isa At-Tirmidhi, An-Nasa'i and Ibn Majah recorded that Musa bin Ibrahim bin Kathir related that Talhah bin Khirash said that Jabir bin `Abdullah said that the Messenger of Allah said,
(The best Dhikr (remembering Allah) is La ilaha illallah and the best supplication is Al-Hamdu Lillah.)
At-Tirmidhi said that this Hadith is Hasan Gharib. Also, Ibn Majah recorded that Anas bin Malik said that the Messenger of Allah said,
(No servant is blessed by Allah and says,`Al-Hamdu Lillah', except that what he was given is better than that which he has himself acquired.) Further, in his Sunan, Ibn Majah recorded that Ibn `Umar said that the Messenger of Allah said,
(A servant of Allah once said, `O Allah! Yours is the Hamd that is suitable for the grace of Your Face and the greatness of Your Supreme Authority.' The two angels were confused as to how to write these words. They ascended to Allah and said, `O our Lord! A servant has just uttered a statement and we are unsure how to record it for him.' Allah said while having more knowledge in what His servant has said, 'What did My servant say' They said, `He said, `O Allah! Yours is the Hamd that is suitable for the grace of Your Face and the greatness of Your Supreme Authority.' Allah said to them, `Write it as My servant has said it, until he meets Me and then I shall reward him for it.)
Al before Hamd encompasses all Types of Thanks and Appreciation for Allah
The letters Alif and Lam before the word Hamd serve to encompass all types of thanks and appreciation for Allah, the Exalted. A Hadith stated,
(O Allah! All of Al-Hamd is due to You, You own all the ownership, all types of good are in Your Hand and all affairs belong to You.)
source: Tafseer Ibn Katheer - Surah Fatiha