verse, or the sequential verse number. Verses Q.2:190, Q.2:191 and Q.2:192, for example, were revealed to Muhammad six years after the verse Q.2:193. Thus chronology depends on "the agreement of scholars" (ijma) and on Tafsir reports or the recollection of Hadith transmitters to explain which verse or prophetic statement was revealed before another. (According to at least one non-Muslim scholar — Andrew Rippin — naskh texts in Islam have not demonstrated that verses rendered invalid by shariah law were revealed earlier, but simply assumed they must have been.) Types/varieties Implicit and explicit naskh Most cases of naskh are "implicit" (dimni) — i.e. as noted above they depend on "the agreement of scholars" (ijma) to determine if a verse was abrogated. However, a few revelations involve "explicit" (sarih) naskh, specifically mentioning some earlier command to be abrogated and replaced with another — though none of them use any form of the word naskh. Quranic verses 2:143-50 commands Muhammad and the Muslims to turn their faces away from 'the direction of prayer that you faced before' (Jerusalem) to a new one, one that 'pleases your heart,' (by which is meant the Kaaba in the Al-Haram Mosque of Mecca). In one hadith Muhammad is reported to have said: 'I had prohibited you from visiting graves, but visit them, for indeed in visiting them there is a reminder [of death].' Total and partial naskh Abrogation may be divided into two more types: total abrogation and partial abrogation: "Total abrogation" In the case of "total abrogation" (or naskh kulli), all of the specific statement within the Quran or hadith that the ruling is based on (the nass) is abrogated by another, and a new ruling (hukm) is enacted to replace the entire old ruling. An example is found in two Qur'anic verses on the waiting period (`iddah) of widows before remarriage. Al-Baqarah 240 has been interpreted to prescribe a waiting period of one year: But another verse shortened the waiting period to four months and ten days: "Partial abrogation" In the case of "partial abrogation" (naskh juzi), one verse is only partially abrogated by another. The part not abrogated remains operative. An example of this is the Qur'anic verse on slanderous accusations of adultery against women (known as qadhf). The "ayah of qadhf" — An-Nur 4 — establishes a general rule that anyone who accuses chaste women of adultery (zina) must produce four witnesses for