Abu Dawud

Benefits and Issues:
➊ This narration is weak in its chain of transmission. However, this narration has also been transmitted through several other routes, and therefore, according to some researchers, it becomes strong due to these routes. [الموسوعة الحديثية43؍265‘266]
Shaykh al-Albani rahimahullah has also graded it as hasan. See: [مشكوة للالبانى‘حديث : 441]
Moreover, the issue mentioned in this narration is also established by a narration in Sahih Muslim, in which Sayyidah Umm Sulaym radi Allahu anha came to the Prophet sallallahu alayhi wa sallam and asked: “If a woman experiences a wet dream (i.e., nocturnal emission), is ritual bath (ghusl) obligatory upon her just as it is upon a man?” The Prophet sallallahu alayhi wa sallam replied: “Yes, if she sees the fluid.” [صحيح مسلم الحيض حديث : 313]
From this, it is clear that there is no difference between men and women in this matter. Whoever experiences a wet dream (in a state of sleep), whether they remember it or not, but if their clothes are wet, then ritual bath (ghusl) is obligatory upon them—provided that their clothes are not wet in the manner of being wet with urine, because in that case ritual bath (ghusl) will not be obligatory. And if they remember having a wet dream in their sleep, but there is no sign (moisture) on their clothes, then ritual bath (ghusl) is not obligatory.

1:
In reality, due to deficiency in memorization, Abdullah al-‘Umari is considered weak by all the Imams. However, the last portion of this hadith is narrated in the Sahihayn from the hadith of Umm Salamah radi Allahu anha, and the first portion is strengthened by the hadith of Khawlah bint Hakim—which is hasan (good)—and thus is authentic (the hadith of Khawlah is in Ibn Majah; see number: 602).

Note:
(The statement of Umm Salamah (or Umm Sulaym) is found only in this narration of Abdullah al-‘Umari, and he is weak. Authentic corroborating reports exist for the remaining portions. See: Sahih Sunan Abi Dawud 234)