The most trustworthy handhold is mentioned in two places in the Holy Qur’aan:
In Soorat al-Baqarah, Allaah says (interpretation of the meaning):
“There is no compulsion in religion. Verily, the Right Path has become distinct from the wrong path. Whoever disbelieves in Taaghoot (false gods etc) and believes in Allaah, then he has grasped the most trustworthy handhold that will never break. And Allaah is All-Hearer, All-Knower”
And in Soorat Luqmaan, Allaah says (interpretation of the meaning):
“And whosoever submits his face (himself) to Allaah, while he is a Muhsin (good‑doer, i.e. performs good deeds totally for Allaah’s sake without any show-off or to gain praise or fame and does them in accordance with the Sunnah of Allaah’s Messenger Muhammad (peace and blessings of Allaah be upon him), then he has grasped the most trustworthy handhold [Laa ilaaha illAllaah (none has the right to be worshipped but Allaah)]. And to Allaah return all matters for decision”
The most trustworthy handhold is also mentioned in the Sunnah, in a hadeeth narrated by al-Bukhaari (3813) and Muslim (2484) from Qays ibn ‘Abbaad who said: I was in Madeenah with some people, among whom were some companions of the Prophet (peace and blessings of Allaah be upon him), when a man came on whose face were signs of the fear of Allaah. Some of the people said: This man is one of the people of Paradise, this man is one of the people of Paradise. He prayed two rak’ahs, making them short, then he went out. I followed him, and he entered his house, and I entered, and we spoke together. When he was at ease, I said to him: When you came in before, a man said such and such. He said: Subhaan Allaah! No one should say what he does not know. He said: Shall I tell you why that is? I saw a dream at the time of the Messenger of Allaah (peace and blessings of Allaah be upon him), and I told him about it. I saw myself in a garden –and he mentioned its vastness and richness and lushness – and in the middle of the garden there was a pillar of iron. Its base was in the earth and its top was in the sky, and at the top of it there was a handhold. It was said to me: Climb it. I said: I cannot. Then a helper came to me and he pushed me up from behind. So I climbed until I was at the top of the pillar, and I took hold of the handhold. It was said to me: Hold it tightly.
I woke up and it was in my hand. I told the Prophet (peace and blessings of Allaah be upon him) about it, and he said: “That garden is Islam, and that pillar is the pillar of Islam, and that handhold is the most trustworthy handhold. You will remain a Muslim until you die.”
He said: And the man was ‘Abd-Allaah ibn Salaam.
The righteous salaf explained the meaning of the most trustworthy handhold in various ways, all of which indicate the same meaning. Ibn ‘Abbaas, Sa’eed ibn Jubayr and al-Dahhaak said: It means Laa ilaaha ill-Allaah.
Anas ibn Maalik said: It is the Qur’aan.
Mujaahid said: It is faith.
Al-Saddi said: It is Islam.
It was narrated from Saalim ibn Abi’l-Ja’d: It is love for the sake of Allaah and hate for the sake of Allaah.
See: Tafseer Ibn Abi Haatim (2/496).
Ibn Katheer said in Tafseer al-Qur’aan al-‘Azeem (1/684):
All these reports are saheeh and there is no contradiction between them. End quote.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was asked in Fataawa Noor ‘ala al-Darb (al-salaah/1218): What is the most trustworthy handhold?
The most trustworthy handhold is Islam. It is called a most trustworthy handhold because it leads to Paradise. End quote.
You can see that the meaning given by the scholars to the most trustworthy handhold is that which leads the one who holds onto it to Paradise. That includes Islam, faith, the Qur’aan and the word of Tawheed (laa ilaaha ill-Allaah). Each of the scholars focused on one of these meanings, which are all close in meaning.
And Allaah knows best.