Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
Poison in a dream is unlawful money or worry and grief. Drinking it indicates falling into strife or illness. Whoever sees himself give poison to another is plotting against him.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
Poison indicates long life. It may also indicate wealth. Whoever drinks it and is not harmed will gain wealth and benefit.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
Poison is interpreted as unlawful money. Whoever sees himself eat it is consuming unlawful money.