1)
What sin did she have?
1.
Rashi: She said so initially so he would hear her words; afterwards, she said the truth - I did not see your youths (verse 25).
2.
Radak: You think that I sinned - hear my words!
3.
Malbim: Naval is like nothing. He has wealth, but he does not eat from it. He is known to be wealthy only due to me. Were I not his wife, you would not send to him. If so, the sin is mine! However, listen