Reference for Menachot 63:5
דאמר רבה אמר רב כהנא אמר רב אם יבא אליהו ויאמר חולצין במנעל שומעין לו אין חולצין בסנדל אין שומעין לו שכבר נהגו העם בסנדל
For Rabbah said in the name of R'Kahana who had it from Rab, If Elijah were to come and say that halizah<span class="x" onmousemove="('comment',' lit., 'drawing off' sc. the shoe; v. Deut. XXV, 5-9. The adopted practice was for the widow to take off a sandal from the foot of her brother-in-law. There was some doubt, however, whether the ceremony may be performed with a covered shoe instead of a sandal. Cf. Yeb. 102a.');"><sup>5</sup></span> may be performed with a covered shoe, he would be obeyed; [were he, however, to say] that halizah may not be performed with a sandal, he would not be obeyed, for the people have long ago adopted the practice [of performing it] with a sandal.