Shepherd of Hermas 25:1
1 As I prayed in the house, and sat on the couch, there entered a man glorious in his visage, in the garb of a shepherd, with a white skin wrapped about him, and with a wallet on his shoulders and a staff in his hand. And he saluted me, and I saluted him in return. 2 And he immediately sat down by my side, and he saith unto me, "I was sent by the most holy angel, that I might dwell with thee the remaining days of thy life." 3 I thought he came to tempt me, and I say unto him, "Why, who art thou? For I know," say I, "unto whom I was delivered." He saith to me, "Dost thou not recognize me?" "No," I say. "I," saith he, "am the shepherd, unto whom thou wast delivered."
Tertullian On Prayer 16
Again, for the custom which some have of sitting when prayer is ended, I perceive no reason, except that which children give. For what if that Hermas, whose writing is generally inscribed with the title The Shepherd, had, after finishing his prayer, not sat down on his bed, but done some other thing: should we maintain that also as a matter for observance? Of course not. Why, even as it is the sentence, When I had prayed, and had sat down on my bed, is simply put with a view to the order of the narration, not as a model of discipline. Else we shall have to pray nowhere except where there is a bed! Nay, whoever sits in a chair or on a bench, will act contrary to that writing. Further: inasmuch as the nations do the like, in sitting down after adoring their petty images; even on this account the practice deserves to be censured in us, because it is observed in the worship of idols. To this is further added the charge of irreverence — intelligible even to the nations themselves, if they had any sense.
Notes and References
"... In his 'Treatise on Prayer' Tertullian described the attitude required and correct posture for different occasions of Christian prayer ... Hermas' stated in his 'Vision Fifth' that he sat after praying, 'After I had been praying at home, and had sat down on my couch.' It appears that some Christians had taken the example of Hermas, from his popular writings called the Shepherd of Hermas c. 160CE, as a guide to Christian practice ..."
Milroy, Leon Francis Prayer in Earliest Christianity in the Context of the Graeco-Roman World (pp. 56-57) University of New England, 2001