Reference: Sifatus-Safwah – Volume 2, Page 401
Abu Bakr an-Neesaabooree narrates:
I visited Ibraaheem ibn Haani whilst he was on his deathbed. [Whilst there] he called his son Ismaa’eel and said to him: Has the sun set [yet]?
He (Ismaa’eel) replied: No.
He then said: O my father, [the likes of] you are permitted to break your fast [in such a severe situation, even] when the fast is obligatory, though your fast is [only] voluntary; Take it easy (don’t burden yourself).
Then he (Abu Bakr an-Neesaabooree) said:
{For the like of this, let the workers work}, [Soorah as-Saaffaat, Aayah 61]
…and then his (Ibraaheem’s) soul departed.