Your request has been heard and I am joining you in prayer about this tension at work. It is painful when you respect your employer and want to do your work well, yet you cannot meet a particular request and you fear their anger and lasting animosity.
Scripture shows that God is able to soften a heart that is angry. When Jacob was about to meet Esau after many years, he feared his brother's anger and did what he could to show humility and goodwill, but the real change came from the Lord. By the time they met, the bitterness of years had been taken away, and instead of recriminations there was embrace and forgiveness and they wept together. In the same way, God can calm anger and bring peace to a meeting that you fear will be tense. Pray that He will work in your employer's heart as well as your own, and trust Him to do what only He can do.
The Lord is our peace, and He can give you peace even in the middle of conflict. That does not always mean the conflict disappears immediately, but it means you can look beyond the present strain to the peace He has promised His people and rest in Him while you wait.
God also calls employees to a faithful witness. We are taught to be obedient to those who employ us, with sincerity of heart as unto Christ, not merely to please people but to serve the Lord. That means doing the best job you can, showing respect, and leaving a good witness. If an employer is a believer, we are not to take advantage of that relationship, but to serve even more diligently because we are brothers in that sense. For employers, the Word says to forbear threatening, remembering that they also have a Master in heaven and there is no partiality with Him. You are right to want respect to go both ways, and God sees and honors a respectful and diligent spirit.
The Bible is honest about anger. There is an anger that is not sinful, such as anger at evil and injustice, and Jesus Himself showed anger at the hardness of heart that would keep people from receiving God's help. But we are also told, be angry and do not sin, do not let the sun go down on your wrath. Bitterness and wrath and anger and clamor and evil speaking grieve the Holy Spirit and are to be put away. We see how serious this is in the lives of Simeon and Levi, whose fierce anger led them to slay a city, and later their father said cursed be that anger, and they lost the place of blessing because of it. God does not hide the sins of men, and He shows us the cost of uncontrolled temper so we will turn from it.
Remember too that the deepest conflict is spiritual. The enemy often hides behind practical pressures and tries to draw us into strife with one another. Our strength is in prayer and in walking in the Spirit, building others up rather than tearing down.
Faith is not passive, so continue to do what is right and respectful in your position. Communicate humbly, do your work with care, and commit the outcome to the Lord.
Let us pray together. Father, in the name of Jesus I lift up this dear one and this employer to You. You see the concern about this missed day and the fear of anger and animosity. I ask that You would calm every heart, take away anger and bitterness, and give a spirit of understanding and respect on both sides. Let the next meeting be marked by grace and not by tension. Help Your child to be a faithful and respectful worker, serving as unto Christ and leaving a good witness. Grant Your peace that passes understanding, and let Your will be done in this workplace. In Jesus name, Amen.