Qays ibn al-Rabīʿ narrated to us. (Another chain:)
And Qutaybah narrated to us, saying: ʿAbd al-Karīm al-Jurjānī narrated to us, from Qays ibn al-Rabīʿ — the meaning is the same — from Abū Hāshim, from Zādhān, from Salmān, who said: I read in the Torah: "Indeed, the blessing of food is the ablution after it." So I mentioned that to the Prophet ﷺ and informed him of what I had read in the Torah. The Messenger of Allah ﷺ said: "The blessing of food is the ablution before it and the ablution after it."(1)

In this chapter, there is also a narration from Anas and Abū Hurayrah.

We do not know this hadith except from the narration of Qays ibn al-Rabīʿ, and Qays is considered weak in hadith.

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Aḥmad declared Qays ibn al-Rabīʿ weak. Muhannā said, as quoted by Ibn Mufliḥ in al-Ādāb al-Sharʿiyyah (3/213): I mentioned it to Yaḥyā ibn Maʿīn, and he said: "How excellent is the ablution before it and after it."

Al-Khallāl said: Abū Bakr al-Marwazī informed us, saying: I saw Abū ʿAbd Allāh washing his hands before food and after it, even if he was already in a state of ablution.

Shaykh Aḥmad Shākir and his colleague, may Allah have mercy on them, said: This is undoubtedly the correct view, because the hands come into contact with dirt, filth, and dust that make the food unclean and spoil it, thereby harming the eater. And the fact that it is from the customs of the non-Arabs does not prevent it from being a good practice, for we have not been commanded to oppose them in everything, even in what sound nature requires and to which the word of Islam calls — namely, purity and cleanliness, and keeping away from all filth and harm.

(1) A weak hadith, due to the weakness of Qays ibn al-Rabīʿ. Abū Dāwūd recorded it (3761), and it is in Musnad Aḥmad (23732).

What is meant by "ablution" here is cleaning the hands by washing them. Al-Ṭībī said: The meaning of its blessing before it is its growth and increase in benefit, and after it is the repelling of the harm of the greasiness that clings to one's hand and its offensiveness.