Hadith: Among them are those whom the fire will reach up to their ankles, others up to their knees, others up to their waists, and others up to their collarbones

عن سمرة بن جندب رضي الله عنه : أن نبي الله صلى الله عليه وسلم قال: «منهم مَنْ تَأْخُذُهُ النَّارُ إلى كَعْبَيْهِ، ومنهم مَنْ تَأْخُذُهُ إلى رُكْبَتَيْهِ، ومِنْهُم مَنْ تَأْخُذُهُ إلى حُجْزَتِهِ، ومنهم مَنْ تَأْخُذُهُ إلى تَرْقُوَتِهِ».
[صحيح] - [رواه مسلم]

Samurah ibn Jundub (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Among them are those whom the fire will reach up to their ankles, others up to their knees, others up to their waists, and others up to their collarbones."
[Authentic hadith] - [Narrated by Muslim]

Explanation

This Hadīth highlights fear of the Day of Judgment and of the torment of Hellfire. The Prophet (may Allah's peace and blessings be upon him) clarified that there are people on the Day of Judgment who will be taken by fire up to their ankles, others up to their knees, others up to their waists, and others up to their necks. People will vary in terms of punishment according to their deeds in the worldly life.