Surah Taha 20:25
قَالَ رَبِّ ٱشْرَحْ لِى صَدْرِى
[Moses] said, "My Lord, expand [i.e., relax] for me my breast [with assurance]
Translation: Saheeh International
Tafsir
He said ‘My Lord expand my breast for me expand it so that it may accommodate the weight of the Divine Message.
Excerpt from Tafsir al-Jalalayn, commentary on 20:25, via Quran.com. The reader has the full commentary and 9 more tafsirs.