Rejoining previous company and H1b visa issues


I have left Employer A and joined Employer B on receipt notice. It is being 1 month since I have joined Employer B.

Through Employer A my I-797 is valid till June 2019. Now Employer A requesting me to join back. I want to know, is it safe to join Employer A again?

Can I find out whether my H1b petition with Employer-A is being revoked?

Thank you in advance.

If Employer A has not revoked or withdrawn, you may join back, if all the terms are same. You need to validate this with the immigration attorney at Employer A, if there are any implications and things you need to take care, if any issues.