The bèi construction, being a narrative sentence about something that has happened, is always negated by 没(有) méi (yǒu), which is placed immediately before bèi. In a negative bèi sentence, 了 le, of course, is not present after the complement:
yī fú méi（yǒu）bèi yǔ lín shī 。
The clothes were not (made) wet by the rain.
xiǎo nǚ hái méi（yǒu）bèi huǒ shāo shāng 。
The little girl was not burnt by the fire.
 Yip, P. C., Rimmington, D., Xiaoming, Z., & Henson, R. (2009). Basic Chinese: a grammar and workbook. Taylor & Francis.