Musannaf Ibn Abi Shayba 3:2501

Ishaq al-Azraq narrated to us, from Hisham, from al-Hasan, that he disliked for a man to lean upon something during the obligatory prayer, unless there was an excuse. And he saw no harm in it during the voluntary prayer. And Ibn Sirin used to dislike it in both the obligatory and the voluntary prayer.