A man reported,

The Messenger of Allah ﷺ prayed the afternoon prayer, and a man stood up to pray afterward. Umar saw him and said to him, "Sit down. The People of the Book were ruined only because there was no clear separation between their prayers."The Messenger of Allah ﷺ said, "Ibn al-Khattab has done well."

Azami 2468

Sahih

عن رجل من أصحاب النبي ﷺ

أن رسول الله ﷺ صلى العصر، فقام رجل يصلي فرآه عمر فقال له: اجلس، فإنما هلك أهل الكتاب أنه لم يكن لصلاتهم فصل فقال رسول الله ﷺ: أحسن ابن الخطاب.

الأعظمي 2468صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Prayer
Chapter
Sunnah prayers and voluntary prayers in general
Section
Completing the shortfall in obligatory prayers with voluntary prayers on the Day of Resurrection
Numbering
Jami al-Kamil 2468 (2nd edition)
Azami 2468