مناسك حج - مكارم شيرازى، ناصر - الصفحة ٢٢١ - Umrah al -Mufradah

Article ٣٥٦- No one is permitted to enter Mecca without Ihram by any reason and should perform Umrah al- Mufradah after Ihram, and does not come out of Ihram without that, but some groups are excluded from this ruling: Car drivers and servants of caravans and all persons who goes out of Mecca( for example to Medina and Jeddah )frequently, also the person who has performed Umrah al- Tamattu or Umrah al- Mufradah and goes out of Mecca and returns in the same lunar month, Ihram and Umrah is not obligatory for this person.

Article ٣٥٧- Performing Umrah is Mustahab in each month; therefore if a person enters Mecca in the ends of month of Rajab and performs Umrah, he/ she can perform Umrah again when the month of Shaban begins, but performing two Umrah al- Mufradah has problem in that same month and if a person wants to perform more than one Umrah in one month, he/ she performs that with the intention of Rija, which means hoping Allah to accept that( not with the intention of an absolute order ).