What is the meaning of "بيض له" (bayyaḍa lahu), as mentioned at the end of the hadith: "Narrated from 'Aishah, and Al-Daylami did not ascertain its chain of transmission, so he 'bayyaḍa lahu'"? And does it indicate the degree of the hadith?

First: The term "bayyad lahu" (بيّض له - literally "whiten for it" or "leave it blank") means to leave a blank space in a book to insert a specific text when it becomes available. It has no relation to the grade of a hadith or to hadith sciences.

Second: The hadith «Cool your food; blessings will be bestowed upon you therein» is weak and Munkar (denounced). However, there is evidence indicating the desirability of leaving food until its intense heat subsides, such as the hadith of Asma bint Abi Bakr, narrated by Imam Ahmad and Al-Darimi, and authenticated by Al-Albani, which states that the Prophet, peace and blessings be upon him, said concerning covering food until its steam dissipates: «Verily, it is greater for blessings.»