Ubada bin Samit reported,

He reported that he entered upon him while he was dying and began to weep. He said, "Wait, why are you weeping? By Allah, if I am granted martyrdom, I will surely bear witness on your behalf. If I am permitted to intercede, I will surely intercede for you. And if I am able, I will surely benefit you."Then he said, "By Allah, there is not a single hadith I heard from the Messenger of Allah ﷺ containing good for you that I have not already related to you, except for one hadith, and I will tell it to you today, for death has now encompassed me. I heard the Messenger of Allah ﷺ say, 'Whoever testifies that there is no god but Allah and that Muhammad is the Messenger of Allah, Allah forbids the Fire upon him.'"

Tirmidhi 2638

Sahih

حدثنا قتيبة حدثنا الليث عن ابن عجلان عن محمد بن يحيى بن حبان عن ابن محيريز عن الصنابحي

عن عبادة بن الصامت

أنه قال دخلت عليه وهو في الموت فبكيت فقال مهلا لم تبكي فوالله لئن استشهدت لأشهدن لك ولئن شفعت لأشفعن لك ولئن استطعت لأنفعنك ثم قال والله ما من حديث سمعته من رسول الله ﷺ لكم فيه خير إلا حدثتكموه إلا حديثا واحدا وسوف أحدثكموه اليوم وقد أحيط بنفسي سمعت رسول الله ﷺ يقول من شهد أن لا إله إلا الله وأن محمدا رسول الله حرم الله عليه النار

الترمذي 2638صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami Tirmidhi
Book
Faith
Chapter
Whoever dies while testifying that there is no god but Allah
Numbering
Darussalam 2638
Tirmidhi 2638