Narrated Ziyad as-Sahmi:

Allah's Messenger (ﷺ) forbade that a stupid woman may be asked to suckle an infant. [Abu Dawud reported it. It is Mursal (missing link after the Tabi'i) and Ziyad is not a Sahabi].

وَعَنْ زِيَادِ اَلسَّهْمِيِّ ‏- رضى الله عنه ‏- قَالَ: { نَهَى رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-أَنْ تُسْتَرْضَعَ اَلْحَمْقَى.‏ } أَخْرَجَهُ أَبُو دَاوُدَ وَهُوَ مُرْسَلٌ, وَلَيْسَتْ لِزِيَادٍ صُحْبَةٌ [1]‏ .‏