The sixth century Digest of Justinian (22.3.2) provides, as a general rule of evidence: Ei incumbit probatio qui dicit, non qui negat[REF]"Proof lies on him who asserts, not on him who denies" [REF].
After the time of Muhammad, the fourth Caliph Ali ibn Abi Thalib has also been cited to say 'Avert the prescribed punishment by rejecting doubtful evidence.'[REF] .