Bukhari

Hadith Commentary:

Al-Khattabi said: This supplication carries two possible meanings: ➊ That he is dragged by his face so that his forehead touches the dust; and ➋ That it is a supplication for obedience for him, so he prays and his forehead touches the dust (i.e., in prostration). Al-Dawudi said: This is an expression commonly used by the Arabs, and its literal meaning is not intended. (Ayni)

That is, this supplication also holds the possibility that the person is dragged on his face and his forehead touches the dust, or it could be a good supplication for him, that he prays and, in the state of prostration during prayer, his forehead touches the dust.

Dawudi said that this is such an expression which is generally current on the tongues of the Arabs, and its literal reality is not intended.

Hadith Commentary:
(1)
Sabbaab, fahaash, and la’aan are all intensive forms, meaning one who curses excessively, one who speaks obscenities excessively, and one who invokes curses excessively. The negation of the intensive form does not necessarily negate the basic act itself, but in this hadith, the negation of the basic act is intended; that is, the Messenger of Allah (sallallahu alayhi wa sallam) was absolutely not someone who cursed, spoke obscenities, or invoked curses.

(2)
The difference among these three is as follows: La’nah (curse) means being distanced from the mercy of Allah. Sab (cursing) pertains to lineage, whereas fahsh (obscenity) pertains to personal character.

(3)
The noble statement of the Messenger of Allah (sallallahu alayhi wa sallam), “May his forehead be soiled with dust,” also has two meanings:
• That he falls on his face and his forehead becomes soiled with dust.
• That when he prays, his forehead touches the earth, i.e., he performs prayer and his forehead meets the dust. In this case, it is a good supplication, but this meaning is not intended here, because among the Arabs, this phrase was already a common proverb before the command of prayer.
In any case, the literal meaning of this phrase is not intended, because this expression would flow spontaneously from the tongues of the Arabs.
And Allah knows best.

Hadith Commentary:
Your statement here also would not have any effect in the manner of a curse, because you had already supplicated to Allah the Exalted:
“O my Lord! If I ever speak ill of anyone, then make it a means of goodness for him.”

Hadith Commentary:
(1)
Cursing someone and using abusive language is a very grave offense. By doing so, a person is deprived of many honors in the sight of Allah Almighty, as the Messenger of Allah (sallallahu alayhi wa sallam) has stated:
“Those who are excessively given to cursing will not be accepted as intercessors or witnesses for anyone on the Day of Resurrection.”
(Sunan Abi Dawud, Al-Adab, Hadith: 4907)
(2)
How great a deprivation it is that a person, by cursing and reviling someone, is deprived of that virtue which would have been a means of his honor on the Day of Resurrection, even though the believers will intercede for their relatives and other people on the Day of Resurrection and will also bear witness in their favor.
Wa Allahu al-musta‘an.

Benefit:
From this hadith, it is established that the science of al-jarh wa al-ta'dil (criticism and accreditation of narrators) is absolutely correct, and it is also proven from this that if a person has some deficiency or shortcoming and wishes to speak with you, then one should speak to him gently. It is permissible to shun a person of bad character, and a person of corrupt character is indeed very evil in the sight of Allah, may Allah protect us, ameen.