Forty Hadiths of al-Nawawi.
On the authority of Mu'adh ibn Jabal (may Allah be pleased with him), who said:
I said, "O Messenger of Allah, inform me of a deed that will admit me into Paradise and keep me far away from the Fire."
He said, "You have indeed asked about a monumental matter,
yet it is easy for whomever Allah Almighty makes it easy.
You shall worship Allah without associating anything with Him,
perform the prayer,
pay the zakat,
fast Ramadan,
and perform Pilgrimage to the House."
Then he said,
"Shall I not guide you to the gates of goodness?
Fasting is a shield,
and charity extinguishes sin
just as water extinguishes fire,
and so does a man's prayer in the depths of the night."
Then he recited:
“Who forsake their beds to cry unto their Lord in fear and hope, and spend of that We have bestowed on them.” (32:16)
until he reached "what they used to do."
Then he said,
"Shall I not inform you of the head of the matter, its pillar, and the apex of its hump?"
I said, "Yes, O Messenger of Allah."
He said, "The head of the matter is Islam,
its pillar is the prayer,
and the apex of its hump is jihad."
Then he said,
"Shall I not inform you of the foundation of all that?"
I said, "Yes, O Messenger of Allah."
So he took hold of his tongue and said,
"Restrain this."
I said, "O Prophet of Allah,
will we truly be held accountable for what we speak with it?"
He replied,
"May your mother be bereaved of you!
Does anything cast people into the Fire on their faces—
or he said: on their nostrils—
other than the harvests of their tongues?"
Narrated by al-Tirmidhi,
who said it is a good and authentic hadith.
The hadith indicates that the greatest means of entering Paradise
is the tawhid of Allah
and the establishment of the pillars of Islam,
including prayer, zakat, fasting, and Pilgrimage;
followed by engaging abundantly in the gates of goodness,
such as charity, voluntary fasting, and the night prayer.
The Prophet (peace and blessings of Allah be upon him) also emphasizes
the grave danger of the tongue,
and that guarding it is among the greatest means of salvation.