as for those who accuse their own spouses but have no witnesses except themselves the testimony of one of them is equivalent to four testimonies if he swears by god that he is truthful.
والذين يرمون أزواجهم ولم يكن لهم شهداء إلا أنفسهم فشهادة أحدهم أربع شهادات بالله إنه لمن الصادقين