Q 20: What is the textual proof of making knowledge of the meaning of the Shahadah a condition for pronouncing it?
A ---Allah the Almighty says: {Except for those who bear witness to the truth knowingly} i.e. believe in the Oneness of Allah, {and they know}. (Az-Zukhruf, 86) i.e. they know in their heart the facts about the Oneness of Allah and its meaning.
Prophet Muhammad (Peace be upon him) says: "He who died knowing (fully well) that there is no god but Allah entered Paradise ". (Sahih Muslim)
Reference: 200 FAQ On Muslims Belief - Shiekh Hafiz Ibn Ahmed Al Hakami