Making Up Missed Prayers, - Dought & clear, - * He did not know that ghusl from janaabah is obligatory; should he repeat the prayers?

I did not know that it is obligatory to do ghusl from janaabah (full
ablution following sexual activity) in order to pray. Do I have to
repeat the prayers?.
Praise be to Allaah.
Every Muslim, male or female, has to learn the rulings of Islam,
especially those that have to do with the duties that Allaah has
enjoined upon him and that he is able to do. Whoever has wealth has to
learn the rulings on zakaah; whoever works in business has to learn
the rulings on buying and selling. And everyone has to learn the
correct beliefs and what is required of every accountable person, the
rulings on purification and prayer. Allaah has made it easy for us to
seek knowledge in various ways, so many people have no excuse for
saying that they did not know, except negligence.
With regard to this particular matter, which is not knowing that it is
obligatory to do ghusl from janaabah, and that you offered many
prayers whilst in this state, the scholars are of the view that this
is regarded as something that may be excused, so you do not have to
make up the prayers. But you have to do ghusl and repeat the prayer at
the time of which you hear of the ruling. They quoted several reports
as evidence for that:
1 - It was narrated from Abu Hurayrah that the Messenger of Allaah
(peace and blessings of Allaah be upon him) entered the mosque and a
man entered and prayed and greeted the Prophet (peace and blessings of
Allaah be upon him) with salaam and he returned the greeting. Then he
said: "Go back and pray, for you have not prayed." So he went back and
prayed as he had prayed the first time. Then he came and greeted the
Prophet (peace and blessings of Allaah be upon him) with salaam and he
said: "Go back and pray for you have not prayed." This happened three
times, then he said: "By the One Who sent you with the truth, I cannot
do any better; teach me." He said: "When you stand to pray, say
takbeer ("Allaahu akbar"), then recite whatever you can of Qur'aan,
then bow until you are at ease in bowing, then stand up until you are
standing straight. Then prostrate until you are at ease in
prostration, then sit up until you are at ease in sitting, and do that
throughout the whole prayer." Narrated by al-Bukhaari, 724; Muslim,
367. The Prophet (peace and blessings of Allaah be upon him) did not
tell him to make up his past prayers, rather he told him to make up
the current prayer only.
2 - It was narrated that 'Abd al-Rahmaan ibn Abza said: A man came to
'Umar ibn al-Khattaab and said: I have become junub but I cannot find
any water. 'Ammaar ibn Yaasir said to 'Umar ibn al-Khattaab: "Do you
not remember when we were on a journey, you and I (and became junub)?
You did not pray, but I rolled in the dust and prayed. I mentioned
that to the Prophet (peace and blessings of Allaah be upon him) and
the Prophet (peace and blessings of Allaah be upon him) said: 'It
would have been sufficient for you to do this,' and the Prophet (peace
and blessings of Allaah be upon him) struck his palms on the ground
and blew onto them, then he wiped them over his face and hands."
Narrated by al-Bukhaari, 331; Muslim, 368.
'Umar ibn al-Khattaab (may Allaah be pleased with him) did not pray
because he did not know that tayammum is obligatory for the one who
cannot find water. 'Ammaar ibn Yaasir (may Allaah be pleased with him)
did tayammum in a different way because he did not know how to do
tayammum correctly. But the Prophet (peace and blessings of Allaah be
upon him) did not tell them to make up the prayers that they had
missed.
Shaykh al-Islam Ibn Taymiyah (may Allaah be pleased with him) said:
Based on this, if a person did not purify himself as prescribed in
sharee'ah because the text had not reached him, such as if he ate
camel meat and did not do wudoo', then the text reached him and he
came to know that it is obligatory to do wudoo' after eating camel
meat, or if he prayed in a camel pen then the text reached him (which
says that it is not allowed to pray in camel pens), does he have to
repeat the past prayers? There are two opinions, both of which were
narrated from Ahmad.
A similar case is if a man touches his penis and prays, then he finds
out that the one who touches his penis has to do wudoo'.
The correct view in all these cases is that he does not have to repeat
the prayers, because Allaah has forgiven things done by mistake or out
of forgetfulness, and because He says (interpretation of the meaning):
"And We never punish until We have sent a Messenger (to give warning)"
[al-Isra' 17:15]
If a person has not heard of the command of the Messenger of Allaah
(peace and blessings of Allaah be upon him) concerning a particular
matter, then the obligation is not confirmed in his case. Hence when
'Umar and 'Ammaar became junub and 'Umar did not pray and 'Ammaar
prayed after rolling in the dust, the Prophet (peace and blessings of
Allaah be upon him) did not tell either of them to repeat the prayer.
Similarly he did not tell Abu Dharr to repeat the prayers when he was
junub and did not pray for several days. And he did not tell those of
his companions who had eaten until they could distinguish the white
thread from the black thread to make up their fasts, and he did not
tell those who had prayed facing Bayt al-Maqdis (Jerusalem) before
news of the abrogation reached them to make up those prayers.
A similar case is that of the woman who was suffering from istihaadah
(non-menstrual vaginal bleeding) and had not prayed for some time
because she thought that she did not have to pray. There are two views
as to whether such a woman has to make up the prayers she missed. One
view is that she does not have to make up the prayers - as was
narrated from Maalik and others - because when the woman who was
suffering from istihaadah said to the Prophet (peace and blessings of
Allaah be upon him): "I have been bleeding heavily for some time and
it prevents me from praying and fasting," he told her what she should
do in the future, and he did not tell her to make up the prayers of
the past.
It seems to me, based on mutawaatir reports, that with regard to women
and men living in the desert and elsewhere who have reached the age of
puberty and do not know that prayer is obligatory for them, and even
if it is said to such a woman, "You have to pray" and she says, "Not
until I grow up and become an old woman, thinking that the command to
pray is only addressed to old women, and even the followers of some
shaykhs (among the Sufis) groups do not know that prayer is obligatory
for them, according to the correct view, they do not make to make up
past prayers regardless of whether it is said that they were kaafirs
or they were excused for their ignorance.
Majmoo' al-Fataawa, 21/101, 102.
See also the answer to question no. 21806.
It may be noted here that if the questioner was in a place where the
means of acquiring knowledge were available but he was careless and
did not try to find out, then he has to make up the prayers that he
offered without ghusl from janaabah, so long as he is not very old. If
he is very old, he does not have to make them up because of the
hardship that that would cause, because Allaah says (interpretation of
the meaning):
"and [Allaah] has not laid upon you in religion any hardship"
[al-Hajj 22:78]
And Allaah knows best.