Praise be to Allah.
Firstly:
What appears to be the case is that you are suffering from intrusive thoughts (waswas) having to do with matters of purification, and this is a chronic problem; we ask Allah to heal you from it. We have previously explained that intrusive thoughts (waswas) may be dispelled by seeking refuge with Allah and stopping thinking about these things, in the answer to question no. 224718.
Secondly:
If a woman has her menses and becomes junub at the same time, it is prescribed for her to do ghusl to remove janabah during her menses. This has been explained previously in the answer to question no. 91793.
Once her menses ends, she should do one ghusl with the intention of removing the impurity of menses.
Thirdly:
It is sufficient to do one ghusl to remove janabah due to climaxing more than once, as we have explained in the answer to question no. 81772.
Fourthly:
It is sufficient to do one ghusl for both menses and janabah, whether you intend both of them together or you intend to do ghusl for one of them. Ibn Qudamah said in al-Mughni, 1/162: If there are two things that make ghusl obligatory, such as menses and janabah, or the meeting of the two circumcised parts and ejaculation, and a person intends both when purifying himself or herself, that is valid. This is the view of most of the scholars, including `Ata’, Abu’z-Zinnad, Rabi`ah, Malik, ash-Shafa`i, Is-haq and as-hab ar-ra’i. End quote.
It says in al-Iqna` fi Hall Alfaz Abi Shuja`, 1/68: If a woman has to do ghusl for both menses and janabah, it is definitely sufficient for her to form the intention for only one of them. End quote.
Fifthly:
What is required when doing ghusl for janabah is to make the water reach every external part of the body, so if the individual makes the water reach all of his body, then he has done the obligatory ghusl, and everything other than that is Sunnah, as we have explained in the answer to question no. 83172.
And Allah knows best.
Comment