الحمد لله رب العالمين، وصلى الله وسلم على نبينا محمد وعلى آله وأصحابه أجمعين، أما بعد
The first thing that one should call to when calling to the religion, in line with the methodology of the Prophets and Messengers (‘alaihimus-salaam); is to Tawheed and to single Allaah out in worship and not associate anything with Him in worship, the following citations add clarity to this affair:
Shaikh ‘Abdur-Rahmaan bin Hasan bin Muhammad bin ‘Abdil-Wahhaab (rahimahullaah) stated a quote from Shaikh ul Islaam Ibn Taymiyyah (rahimahullaah) in which he said:
“Indeed; it is necessarily known from the religion of the Messenger (sallallaahu ‘alaihi wa sallam), and upon which the Ummah is in agreement upon that; the basis of Islaam and the first thing which the creation are to be commanded with is: the testimony that none has the right to be worshipped except Allaah, and that Muhammad is the Messenger of Allaah.”
Shaikh Sulaimaan bin ‘Abdillaah bin Muhammad bin ‘Abdil-Wahhaab (rahimahullaah) said:
“If one intends to call to that; then he should begin with the call to Tawheed which is the meaning of the testimony that: none has the right to be worshipped except Allaah. Since; the actions are not correct except by way of it, so it is therefore its basis upon which it is then to be constructed upon, and whenever it is not to be found; then action will be of no benefit – rather it is in vain. As worship cannot be correct along with shirk, as He, The Most High, said:
مَا كَانَ لِلْمُشْرِكِينَ أَن يَعْمُرُوا مَسَاجِدَ اللَّهِ شَاهِدِينَ عَلَىٰ أَنفُسِهِم بِالْكُفْرِ أُولَٰئِكَ حَبِطَتْ أَعْمَالُهُمْ وَفِي النَّارِ هُمْ خَالِدُونَ
((It is not for the polytheists to maintain [and visit] the mosques of Allaah while witnessing against themselves with disbelief. The works of such are in vain, and in the Fire they will abide eternally.)) (At-Tawbah: 17)
Likewise because the understanding of the meaning of this testimony is itself the first obligation upon the servants, and it is therefore the first thing which is initiated with when calling.”
Shaikh Rabee’ bin Haadi al-Madkhali (hafidhahullaah) said during his discussion of the reason why the first thing one is to call is Tawheed:
“Why Tawheed first? Because this is the methodology of Allaah which He has legislated for all of the Prophets (‘alaihimus salaatu was-salaam). So there is no Messenger who called his nation except that he began with Tawheed, even if it be that the calls of the Prophets incorporated every good for mankind.
Whoever reflects over the Qur’aan, he will see that the calls of the Prophets share a concurrence in principles that are very immense; from them is: Tawheed, and from them is: affirmation of prophethoods, and from them is the affirmation of the Resurrection and the recompense. However; the fundamental pivot of their calls, as well as that which the strife between them and their nations revolved around, was due to that of Tawheed – and Tawheedul ‘Ibaadah itself.
This is because Tawheed ar-Ruboobiyyah and Tawheed al-Asmaa wa-Sifaat – you do not see any differing in the Qur’aan between a Prophet and his nation in anything from this, they no doubt belied the Resurrection and they denied it, however; that which they belied the most regarding was: the call to making the religion sincerely and purely for Allaah, The Blessed and Most High.
So you can see all the calls of the Prophets, as Allaah has made that clear in His Book; the first thing that they began with was the rectitude of the belief, the rectitude of that which they had violated in the matter of Tawheedul ‘Ibaadah.”
The Shaikh said likewise:
“Be acquainted with the call of the Messengers; as well as the methodology of the Messengers, and know that the issue is not optional, it is a definitive obligation upon everyone who calls to Allaah in truthfulness that he begins with Tawheed, and the proof is that Allaah has legislated this methodology for all of the Prophets.
So the Prophets proceeded upon it, from the first of them to the last of them, and Muhammad (sallallaahu ‘alaihi wa sallam) began with Tawheed, for thirteen years he did not call to the other legislations, the prayer – the most important of the pillars of Islaam – was not legislated until just before the Hijrah. Likewise the zakaat was not legislated except in the Madinan period, due to the importance of Tawheed and because it is the basis, and the Messenger (sallallaahu ‘alaihi wa sallam) did not waver from it by even a single hair’s breadth.
Yet they (the Makkans) came to him seeking any wish from him, if he desired sovereignty; they would give it, if he wanted the finest young woman amongst the Quraish; then they would marry her to him, if he wanted wealth they would give it. Yet he would say; I do not need from you except this, and he would take the pledge of allegiance from the people upon this, and would make Jihaad upon it; meaning Tawheed.”
The Shaikh stated elsewhere on this topic:
“We adjure – by Allaah; the students of knowledge, and we adjure – by Allaah; the callers, that they should not betray this Ummah, and that they should not conceal these clear proofs, as well as this guidance which Allaah has revealed upon Muhammad (‘alaihi salaatu was-salaam); that of: explaining Tawheed, clarifying Tawheed from that of making shirk with Allaah, The Blessed and Most High. Indeed this knowledge; if we lose it, then there is no value for the rest of the sciences.
By Allaah; there is no value for Fiqh, or for anything other than it if we squander ‘Aqeedah (belief) and we squander Tawheed, and we instead fall into making shirk with Allaah, there will be no benefit in any knowledge at all. If we were to memorise the Qur’aan, and we memorized the hadeeth, and we memorized the books of Fiqh, yet we were to fall into the darknesses of shirk; then there is no value to us, and we shall not benefit from this knowledge.
Therefore we will not benefit from the Qur’aan or from the Sunnah or from the sciences – all of them – except if we construct the pillars of Tawheed, and we demolish the fundamentals of shirk with Allaah, The Blessed and Most High, and that we eradicate them from their roots.”
 Fathul Majeed Sharh Kitaab at-Tawheed p.104
 Tayseer al-‘Azeez al-Hameed fee Sharh Kitaab at-Tawheed vol 1 p.299
 Tawheed Awwallan p.2
 Ibid p.10-11
 Marhaban ya Taalib al-‘Ilm p.111