On the Importance of Tawheed
Verily, all the Messengers began their call with Tawheed, which they were commanded by Allah to convey it to the people. He, the Most High, said:
"We have not sent before you from the Messengers, except We inspired to him that He is the only One worthy of worship, so worship Him." [21:25]
The Messenger of Allah (sallallaahu ‘alayhi wa salaam) stayed in Makkah for thirteen years while he called his people to the Tawheed of Allah and he called to Him alone without associating anything with Him. It was regarding this issue that Allah revealed the following verse to His Noble Messenger (sallallaahu ‘alayhi wa salaam):
"Say: Verily I call to my Lord and I do not ascribe any partners to Him at all." [72:20]
The Noble Messenger (sallallaahu ‘alayhi wa salaam) brought up his followers upon Tawheed from the time of childhood and he (sallallaahu ‘alayhi wa salaam) said to the son of his uncle, his cousin 'Abdullaah ibn 'Abbaas: "When you ask, then ask Allah, and when you seek help, then seek help from Allah." [Hasan Saheeh, Tirmidhi]. This Tawheed is in reality the religion of Islam, which is built upon it, and anything other than it is not accepted by Allah.
Verily, the Messenger (sallallaahu ‘alayhi wa salaam) taught his Companions to begin their call to the people with tawheed, so he (sallallaahu ‘alayhi wa salaam) said to Mu'aadh ibn Jabal, when he (sallallaahu 'alayhi wa salaam) sent him to Yemen: "So let the first thing you call them to, be the testification that none has the right to be worshipped except Allah." And in another narration: "...that they worship Allah alone." [Bukhari and Muslim]
Tawheed is embodied in the testification that "None has the right to be worshipped except Allah, and Muhammad is the Messenger of Allah." Its meaning is that there is no one who is worthy of deserving worship except Allah, and there is no worship except that which the Messenger of Allah (sallallaahu ‘alayhi wa salaam) came with. It is this testification which allows a unbeliever to enter into Islam, since it is the key to Paradise, and the one who testifies to it and believes it enters into Paradise as long as he does not invalidate it by shirk or a word of disbelief.
The disbelieving Quraish offered the Messenger of Allah (sallallaahu 'alayhi wa salaam) kingship, wealth and wives and other than that from the pleasures of this life in exchange for him abandon the call to tawheed, and abandon the attacks against the idols. However, he did not desire that from them, rather he (sallallaahu ‘alayhi wa salaam) continued his call and endured the onslaught along with his Companions, until the call to tawheed was victorious after Makkah was conquered and the idols were destroyed. The Messenger of Allah (sallallaahu 'alayhi wa salaam) recited,
"Truth has come and falsehood has vanished, surely falsehood is ever bound to vanish." [17:81]
Tawheed is the preoccupation of a Muslim in his life, so he begins his life with Tawheed and he ends his life with Tawheed. His task in life is to establish Tawheed and the call to Tawheed, since Tawheed unifies the believers and gathers them upon the statement of Tawheed. So we ask Allah to make the statement of Tawheed (Laa ilaaha lila Allah) our last words in this world and we ask Him to gather the Muslims upon the statement of Tawheed - Ameen.