Abu Hurairah reported,
The Messenger of Allah ﷺ said, "Whoever fasts a single day seeking the pleasure of Allah, the Exalted, Allah 
will distance him from Hellfire by a distance equal to that traveled by a crow that took flight as a young chick and kept flying until it died of old age."
Ahmad 10808
Daifحدثنا عبد الله بن يزيد حدثنا ابن لهيعة عن خالد بن يزيد عن لهيعة أبي عبد الله عن رجل قد سماه حدثني سلمة بن قيصر
عن أبي هريرة
أن رسول الله ﷺ قال من صام يوما ابتغاء وجه الله تعالى بعده الله عز وجل من جهنم كبعد غراب طار وهو فرخ حتى مات هرما
No references are available.
Its isnad is daif, it contains an unnamed narrator, and Abdullah bin Lahia and the other narrator are both trustworthy, and Salama bin Qays, whom Tabarani named in 7/56 no. 1315 as Salama bin Qaysar, and he did not narrate it from an unnamed man but rather from Amr bin Rabia Hadrami from Salama bin Qaysar, so it is connected according to him.