Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
suyuti:2421a –

AbulQasim ﷺ said: When one of you is in the sun (Shams)--Makhlad's version has "fay'"--and the shadow withdraws from him so that he is partly in sun and partly in shade, he should get up. (Using translation from Abū Dāʾūd 4821)   

السيوطي:٢٤٢١a –

"إذَا كانَ أحدُكُمْ في الشَّمْسِ فقَلَصَ عنْه الظِّلُّ، وصارَ بَعْضُهُ في الظِّلِ وبَعْضُه في الشَّمس فليقُم".  

[د] أبو داود [ق] البيهقى في السنن عن أبي هريرة

See similar narrations below:

Collected by Abū Dāwūd
abudawud:4821 – Ibn al-Sarḥ And Makhlad b. Khālid > Sufyān > Muḥammad b. al-Munkadir > Man > Abū Hurayrah

AbulQasim ﷺ said: When one of you is in the sun (Shams)--Makhlad's version has "fay'"--and the shadow withdraws from him so that he is partly in sun and partly in shade, he should get up.  

أبو داود:٤٨٢١ – حَدَّثَنَا ابْنُ السَّرْحِ وَمَخْلَدُ بْنُ خَالِدٍ قَالاَ حَدَّثَنَا سُفْيَانُ عَنْ مُحَمَّدِ بْنِ الْمُنْكَدِرِ قَالَ حَدَّثَنِي مَنْ سَمِعَ أَبَا هُرَيْرَةَ يَقُولُ قَالَ

أَبُو الْقَاسِمِ ﷺ إِذَا كَانَ أَحَدُكُمْ فِي الشَّمْسِ وَقَالَ مَخْلَدٌ فِي الْفَىْءِ فَقَلَصَ عَنْهُ الظِّلُّ وَصَارَ بَعْضُهُ فِي الشَّمْسِ وَبَعْضُهُ فِي الظِّلِّ فَلْيَقُمْ