Times when prayer is not offered

No voluntary prayer after Fajr until sunrise, nor after Asr until sunset.

Narrated by Abu Sa'id al-Khudri

There is no prayer after the morning prayer until the sun has risen, and no prayer after the Asr prayer until the sun has set.

Sahih al-Bukhari 586, Sahih Muslim 827

What this hadith teaches

These are the times when voluntary prayers without a reason are not offered, so as not to resemble those who worshipped the sun. Missed obligatory prayers may still be made up.

Reference and grade

Grade
Sahih: agreed upon by al-Bukhari and Muslim
Narrator
Abu Sa'id al-Khudri

The hadith in Arabic نص الحديث

لاَ صَلاَةَ بَعْدَ الصُّبْحِ حَتَّى تَرْتَفِعَ الشَّمْسُ، وَلاَ صَلاَةَ بَعْدَ الْعَصْرِ حَتَّى تَغِيبَ الشَّمْسُ

Arabic text of Sahih al-Bukhari 586, as given on sunnah.com.