In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Allaah [The Mighty and Majestic] said:
وَإِذۡ قَالَ إِبۡرَٲهِيمُ لِأَبِيهِ وَقَوۡمِهِۦۤ إِنَّنِى بَرَآءٌ۬ مِّمَّا تَعۡبُدُونَ
إِلَّا ٱلَّذِى فَطَرَنِى فَإِنَّهُ ۥ سَيَہۡدِينِ
وَجَعَلَهَا كَلِمَةَۢ بَاقِيَةً۬ فِى عَقِبِهِۦ لَعَلَّهُمۡ يَرۡجِعُونَ
And [remember] when Ibraaheem said to his father and his people: “Verily, I am innocent of what you worship, except Him [Allah Alone] Who did create me, and verily, He will guide me”. And he made it a Kalimah [a statement] lasting among his offspring that they may turn back [i.e. to repent to Allah or receive admonition]. [Surah Az-Zukhruf. Aayaat 26-28]
The meaning of Laa ilaaha Ilal laah is found in the above Aayah.
[إِنَّنِى بَرَآءٌ۬ مِّمَّا تَعۡبُدُونَ- Verily, I am innocent of what you worship] is a negation of all acts of worship directed at other objects of worship; and the phrase [إِلَّا ٱلَّذِى فَطَرَنِى – except Him (Allah) Who did create me] is an affirmation that Allaah alone has the right to be worshipped.
[إِنَّنِى بَرَآءٌ۬ مِّمَّا تَعۡبُدُونَ- Verily, I am innocent of what you worship] carries the meaning Laa ilaaha [There is no deity worthy of worship], and [إِلَّا ٱلَّذِى فَطَرَنِى- except Him (Allah) Who did create me] carries the meaning Ilal laah [Except Allaah].
And which Kalimah [statement] did Ibraaheem [alayhis salaam] make a lasting statement amongst his offspring? It is the statement Laa Ilaaha Ilal laah [There is no deity worthy of worship except Allaah].
[Sharh Kitaab At-Tawheed. Lesson 3. By Shaikh Abdur Razaaq Al-Badr [hafidhahullaah]