Quran verses:

Surah An Nur (24): Verse 2
“The fornicatress and the fornicator, flog each of them with a hundred stripes. Let not pity withhold you in their case, in a punishment prescribed by Allah, if you believe in Allah and The Last Day. And let a party of the believers witness their punishment.” From the English Translation of Quran printed by King Fahd ibn’ Abd al Aziz, Al Saud, King of Saudia Arabia, Custodian of the Two Holy Mosques.)

Surah An Nur (24): Verse 3
“The adulterer-fornicator marries not but an adultress-fornicatress or a mushrikah, and the adultress-fornicatress none marries her except an adultery-fornicator or a Mushrik (and that means the man who agrees to) marry a Mushrika or a prostitute, then surely he is either an adulterer-fornicator or a Mushrik. And the woman who agrees to marry a Muskrik or an adulterer-fornicator then she is either a prostitute or a Mushrikah. Such a thing is forbidden to the believers (of Islamic Montheism).” From the English Translation of Quran printed by King Fahd ibn’ Abd al Aziz, Al Saud, King of Saudia Arabia, Custodian of the Two Holy Mosques.) 

Surah An Nur (24): 4
“And those who accuse chaste women and produce not four witnesses flog them with eighty stripes and reject their testimony forever. They indeed are the Fasiqeen (liars, rebellious, disobedient to Allah)” (From the English Translation of Quran printed by King Fahd ibn’ Abd al Aziz, Al Saud, King of Saudia Arabia, Custodian of the Two Holy Mosques.)

Chapter 4: Verse 15
“If any of your women are guilty of lewdness, take the evidence of four (pious/ reliable) witnesses from amongst you against them; and if they testify, confine them to houses until death do claim them, or Allah ordain for them some (other) way.”

Chapter 2: Verse 282
“O ye who believe! When ye deal with each other, in transactions involving future obligations in a fixed period of time, reduce them to writing Let a scribe write down faithfully as between the parties: let not the scribe refuse to write: as Allah Has taught him, so let him write. Let him who incurs the liability dictate, but him feat His Lord Allah and not diminish aught of what he owes. If the party liable is mentally deficient, or weak, or unable Himself to dictate, Let his guardian dictate faithfully, and get two witnesses, out of your own men, and if there are not two men, then a man and two women, such as ye choose, for witnesses, so that if one of them errs, the other can remind her. The witnesses should not refuse when they are called on (for evidence).”