Found it:
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The Rafidhi quotes this Hadith:
[A man came to 'Umar and said: “I have seminal discharges and I
cannot find water (to do the ghusl)”. He (‘Umar) said, “Do not
perform Ṣalāt.” So, ‘Ammar said, “Do you remember, O Amīr al-
Mūminīn, when I and you were in a military detachment and we had
seminal discharges and could not find water and you (‘Umar) did
not perform the Ṣalāt. As for me, I rolled myself in dust and
performed the Ṣalāt. So, the Prophet, peace be upon him, said, “It was
enough for you to strike the soil with your hands and then blow and
then wipe your face and palms”. Umar said: “Fear Allāh, O Ammār!”
Therefore, he (‘Ammār) replied, “If you so like, I would not narrate
it]
He accuses `Umar (ra) of ignorance and disobedience. Something to notice though in the Hadith before we begin, was that `Ammar (ra) himself didn't know how to make Tayammum, also that `Ammar (ra) told `Umar (ra): "If you so like, I would not narrate it."
Just like the Takfeeri Toyib wants to make Takfeer on `Umar (ra) because he disliked for the believers to get lazy when it comesto Tayammum. We can also use the same logic to make Takfeer on `Ammar (ra) who decided to obey `Umar (ra) and please him.
We quote this verse: {Indeed, those who conceal what We sent down of clear proofs and guidance after We made it clear for the people in the Scripture - those are cursed by Allah and cursed by those who curse}
And this Hadith: "There is no obedience for the ruler in disobedience for Allah."
Another point is, the fact that `Ammar (ra) never knew how to do it until the Prophet (saws) taught him, shows that they never did it much. I add, that when the Prophet (saws) lectured `Ammar (ra) on how to properly do it, there is nothing that specifically states that `Umar (ra) heard this lecture.
Regardless of this, Tayammum is permissible in Islam even in Janabah as is declared by the Prophet (saws) in one narration, a man came to him and asked him about it and he (saws) permitted it.
Now the Rafidhi quotes the following verse from the Qur'an about Tayammum:
{O you who have believed, do not approach prayer while you are intoxicated until you know what you are saying or in a state of Janabah, except those passing through [a place of prayer], until you have washed [your whole body]. And if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and find no water, then seek clean earth and wipe over your faces and your hands [with it]. Indeed, Allah is ever Pardoning and Forgiving.} [4:43]
`Umar ibn al-Khattab (ra) and `Abdullah ibn Mas`oud (ra) never heard of the narration of Tayammum apparently, and they practiced based on the apparent meaning of these Qur'anic verses:
{O you who have believed, when you rise to [perform] prayer, wash your faces and your forearms to the elbows and wipe over your heads and wash your feet to the ankles. And if you are in a state of Janabah, then purify yourselves. But if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and do not find water, then seek clean earth and wipe over your faces and hands with it. Allah does not intend to make difficulty for you, but He intends to purify you and complete His favor upon you that you may be grateful.} [5:6]
Notice how this verse separates the ruling of Janabah from the rest of the matters, it says: {And if you are in a state of janabah, then purify yourselves}.
Even in verse [4:43] quoted by the Shia above, they understood from this part that Janabah can only be removed by washing: {O you who have believed, do not approach prayer while you are intoxicated until you know what you are saying or in a state of Janabah, except those passing through [a place of prayer], until you have washed [your whole body].}
Both verse [5:6] and [4:43] state clearly that Janabah is removed by washing.
In other words, they did not hear the narration of Tayammum, and they did not see that the person on Janabah is included in this part of the verse:
{But if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and do not find water, then seek clean earth and wipe over your faces and hands with it.}
They also understood that "contacting women" is anything less than reaching a state of Janabah, such as touching your wife with or without lust without having intercourse.
This is proven by the fact that `Abdullah ibn Mas`oud (ra) narrates:
حدثنا حفص عن أشعث عن الشعبي عن أصحاب عبد الله عن عبد الله قال اللمس ما دون الجماع
[Hafs from al-Ash`ath from al-Sha`bi, from the companions of `Abdullah (ra) that he says: "Contact" is what is less than intercourse. Also narrated by Wakee` from Suffiyan from al-Mugheerah from Ibrahim from `Abdullah (ra)]
With the same chain from the companions of `Ali ibn abi Talib (ra) that he believed that "contacting women" means having intercourse with them. Ibn `Abbas (ra) also believed this but his student Sa`eed ibn Jubayr believed otherwise, and some Imams also differed on this, the reader can refer to the chapter in Musannaf ibn abi Shaybah about the meaning of "contacting women".
I would like to add one more thing after we have clarified the issue. Toyib missed a part of the narration which he did not translate, you see `Umar (ra) never denied `Ammar (ra) or called him a liar, when he heard from him the incident of Tayammum he simply said: "Fear Allah O `Ammar!"
`Ammar (ra) replied by telling `Umar (ra): "If you so like, I would no longer narrate it." This shows that `Ammar (ra) had great trust in `Umar's (ra) religious opinions and judgement.
Then comes the part that Toyib missed to translate:
قال لعمر: إن شئت لم أحدث به ، قال عمر : بل نوليك ما تولـيت
After `Ammar (ra) said this, `Umar (ra) replied: "Nuwallika ma Tawallayt."
In Fath al-Bari by Ibn Hajar, he explains this expression:
أي لا يلزم من كوني لا أتذكره أن لا يكون حقا في نفس الأمر ، فليس لي منعك من التحديث به
[Meaning: It is not necessary that If I do not recall it then it isn't true, so I cannot prevent you from narrating this.]
In Sharh Sunan abu Dawoud by al-`Abad:
يعني: نكلك إلى علمك وإلى ما عندك، ولك أن تعمل وتفتي بهذا
[Meaning: We leave you to your knowledge, and it is permitted for you to practice upon it and to offer it as a verdict.]
This can actually be understood that `Umar (ra) was convinced by the words of `Ammar (ra) and that he accepted his verdict and changed his view on the matter.
Another aspect that the Rafidhi never payed attention to, is that Ibn Mas`oud (ra) was convinced that his opinion was correct, Toyib says that they both did this out of ignorance and disobedience for Allah, whereas Ibn Mas`oud (ra) stated his view:
يوشك أن الرجل إذا برد عليه الماء تيمم وترك الماء
[There is a possibility that they would perform tayammum with soil even if water were available but cold.]
This proves that there was no ill intention, Ibn Mas`oud's (ra) argument was that he fears, that if abu Musa's (ra) understanding is correct, then many people would become lazy and abandon Wudhu' little by little.
This seems sufficient as an explanation, may Allah guide those of evil hearts.
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I got question:
you wrote:
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Then comes the part that Toyib missed to translate:
قال لعمر: إن شئت لم أحدث به ، قال عمر : بل نوليك ما تولـيت
After `Ammar (ra) said this, `Umar (ra) replied: "Nuwallika ma Tawallayt."
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This part isn't found in the hadith mentioned in sahih muslim nor the one I found sahih bukhari. So which hadith did toyib refer to in his book?