The Prophet ﷺ used to deliver his sermon leaning against the trunk of a palm tree, and he then mentioned the same meaning.
حدثناه الخزاعي قال أنبأنا حماد بن سلمة عن عمار بن أبي عمار عن ابن عباس وعن ثابت
أن النبي ﷺ كان يخطب إلى جذع النخلة فذكر معناه
No references are available.
Its isnad is sahih. It belongs to the Musnad of Anas, with Ibn Abbas alongside him, and it carries the same meaning as what preceded it.