A Witness Must Be Fit From Start to Finish

"And he is a witness, whether he has seen" (Leviticus 5:1): if a man knew testimony before he became the litigant's son-in-law and then became his son-in-law, or was clear-minded and became deaf, sighted and became blind, sane and became insane, he is disqualified. But if he knew the testimony before becoming son-in-law and then became son-in-law and the man's daughter died, or was clear-minded and became deaf and then recovered his hearing, or was sane and became insane and then recovered his sanity, he is fit. This is the rule: whoever is fit at the beginning and at the end is fit. For Scripture says "whether he has seen or known; if he does not tell" - the Merciful One made it depend on perception, and that is present. Then why is "he" needed? For what was taught: if a man saw a group of people standing with his witnesses among them, Scripture says "and he is a witness" - the rule does not apply, since he did not single out his witnesses. There was an incident of a man going out to be executed, who said: "If this sin is truly in me, let my death not atone for all my sins; and if this sin is not in me, let my death atone for all my sins. The court and all Israel are innocent, but the witnesses shall never have forgiveness." When the sages heard of the matter they said: to bring him back is impossible, for the decree has already gone forth; rather let him be executed, and let the chain of guilt hang upon the neck of the witnesses. Is this within their power? The case was where the witnesses retracted. But what does it matter if they retract - once a witness has testified, he cannot retract and testify again? The case was where they gave a reason for their words, as in the incident of the one who sought the cup.