All perfect praise be to Allah, the Lord of the Worlds; may His blessings and peace be upon our Prophet Mohammad and upon all his family and companions.
Adultery has disastrous consequences on the person who commits it since sins and misdeeds are the cause of every evil in this life and the next, in addition to lack of provision and deprivation from blessing. Messenger of Allah (Peace and blessings be upon him) said: “A man may be deprived of provision by a sin that he commits.” {Mosnad Ahmad,vol.37/pp.111}.
Scholars have said that adultery has adverse effects on the adulterer reflected on his/her countenance and heart. This is in addition to being despised by others and treated as a traitor. As sin begets sin, adultery is accompanied with disobedience to parents, severance of kinship ties, drinking intoxicants, and violating people`s honor. In the Hereafter, the adulterous will be subjected to severe punishment and degradation.
As for the killer, he/she will be subjected to Qysas (legal retribution) or be forgiven by the relatives of the killed or in the Hereafter, his/her good deeds would be credited to the account of those who suffered at his/her hand.
However, the statement mentioned in the above question isn`t a Hadith of the Prophet (Peace and blessings of Allah be upon him) and wasn`t reported in the books of Hadith. Rather, Imam Al-Sakhawi said, "I don`t know this Hadith" {Al-Maqasid Al-Hasanah No. (93)}. The meaning of the above statement was mentioned in a fabricated Hadith where it was claimed that Ibn Omar (May Allah be pleased with them) narrated that the Messenger of Allah (Peace and blessings be upon him) said {What means}: "Adultery bequeaths poverty." Abu Hatim related this in his book {Al-Elall, vol.1/pp. 410-411}. Abu Hatim said: "this is a false Hadith." Al-Thahabi said, in {Meezan Al-`E`tidal, vol.3/pp.423}, "This is a denied Hadith (Munkar)." And Allah the Almighty Knows Best.