7. Furthermore, it is well established that the Prophet ﷺ would call the disbelievers to Islam by inviting them to accept the two testimonies.

The Prophet ﷺ said: ((أُمِرْتُ أَن أُقاتِلَ النَّاسَ حَتَّى يَشْهَدُوا أَن لا إِلهَ إِلاَّ اللهُ وأَنَّ مُحَمَّدًا رَسُولُ اللهِ)) "I have been ordered (by Allah) to fight against the people until they testify that none has the right to be worshipped but Allah and that Muhammad is Allah's Messenger (ﷺ)." [Agreed upon] The disbelievers at the time of the Prophet ﷺ understood this hadith better than the theologians (Ahlul-Kalaam). Narrated Usama ibn Zaid: The Messenger of Allah ﷺ sent us to Huraqat, a tribe of Juhaina. We attacked that tribe early in the morning and defeated them and I and a man from the Ansar caught hold of a person (of the defeated tribe). When we overcame him, he said: لاَ إِلَهَ إِلاَّ اللهُ ‏ There is no diety worthy of worship but Allah. At that moment the Ansari spared him, but I attacked him with my spear and killed him..." [Agreed upon] The point being, even this man (who was a disbeliever at the time) knew that لا إله إلا الله was the first obligation upon him. He didn't say: give me some time to reflect and contemplate. Buraidah narrated that whenever the Messenger of Allah (ﷺ) appointed anyone as leader of an army or detachment he would especially exhort him to fear Allah and to be good to the Muslims who were with him. He would say, when you meet your enemies who are polytheists, invite them to three courses of action. If they respond to any one of these, you also accept it and withhold yourself from doing them any harm. 1. Invite them to (accept) Islam (I.e. لا إله إلا الله); if they respond to you, accept it from them and desist from fighting against them. 2. If they refuse to accept Islam, demand from them the Jizya. If they agree to pay, accept it from them and hold off your hands. 3. If they refuse to pay the tax, seek Allah's help and fight them. [Sahih Muslim, 1731] The Prophet ﷺ did not give them the option of reflecting and contemplating Allāh's existence. If this was an option, surely many of the kuffar who were too weak to fight the Muslim army would have taken this option and used it as an excuse to continue upon their Kufr under the pretext that "they are still contemplating". 8. If reflection was the first duty/act of worship upon the mukallaf, would it accepted from a person if they haven't yet entered into the fold of Islam?! Reflect over the speech of Ibnul Qayyim in Mada‌rij As-Salikeen: "The station of monotheism is the most appropriate starting point, as it was the first call of all the prophets. The Prophet ﷺ said to Mu'adh ibn Jabal when he sent him to Yemen, "Let the first thing you call them to be the testimony that there is no deity worthy of worship but Allah," and in another narration, "that they know Allah." ولأنه لا يصح مقام من المقامات ، ولا حال من الأحوال إلا به THIS IS BECAUSE NO OTHER STATION OR STATE IS VALID EXCEPT THROUGH MONOTHEISM. Therefore, it makes no sense to place it as the last station, as it is the key to the call of the prophets and THE FIRST OBLIGATION ALLAH IMPOSED ON HIS SERVANTS. Any other opinion is incorrect, such as those who say that the first obligation is contemplation, or the intention to contemplate, or المعرفة, or doubt that necessitates contemplation. All these opinions are wrong. Rather, the first duty is the key to the call of all the messengers, and it was the first thing their leader, Nuh, called to when he said, "O my people, worship Allah; you have no deity other than Him," and it was the first thing their final messenger, Muhammad, peace be upon him, called to." He also said: فالتوحيد أوَّل ما يدخل به في الإسلام وآخر ما يخرج به من الدنيا كما قال النبي من كان آخر كلامه لا إله إلا الله دخل الجنة فهو أول واجب وآخر واجب. "Tawheed is the first step to entering Islam and the last thing one leaves this world with. As the Prophet said, "Whoever's last words are 'There is no deity worthy of worship but Allah' will enter Paradise." Thus, it is the first and the last obligation.