It is recommended to offer a certain prayer on each of the White Nights (i.e. the thirteenth, fourteenth, and fifteenth nights of each Arabic month) in Rajab, Sha’ban, and Ramadan. At the thirteenth night of Rajab, it is recommended to offer a prayer consisting of two units at each of which it is advisable to recite Surah al-Faatehah once and Surahs Yasin (No. 36), al-Mulk (No. 67), and al-Tawheed.
A similar prayer, yet with four units and Taslim after each two units, should be offered at the fourteenth night. Also, a similar prayer, yet with six units and Taslimafter each two units, should be offered at the fifteenth night. In this respect, Imam Ja’far al-Sadiq(a.s.) is reported as saying, “Whoever offers these prayers, will be awarded the merits of these three months (namely, Rajab, Sha’ban, and Ramadan) and will have all his sins forgiven, except polytheism.