Attestation Clause refers to a provision at the end of an instrument where the witnesses certify that the instrument has been executed before them, and the manner of the execution of the same. It states that the instrument has been completed in the manner required by law in the presence of the witness who places his or her signature in the designated space.
The attestation strengthens the presumption that all the statutory requirements for executing the will have been satisfied. When there is an attestation clause to a will, unsubscribed by witnesses, the presumption, though slight, is that the will is in an unfinished state and it must be removed by some extrinsic circumstances.

An attestation clause is frequently found in legal documents that must be witnessed if they are to be valid, for example, a will or a deed.The usual attestation clause to a will is: “Signed, sealed, published and declared by the above named A B, as and for his last will and testament, in the presence of us, who have hereunto subscribed our names as the witnesses thereto, in the presence of the said testator, and of each other.” Deeds generally use the words “Sealed and delivered in the presence of us.”