Is one who does not convey greetings to his father, fearing a problem with him, sinful?

Conveying salams is a trust (amanah (definition)) that must be fulfilled if a Muslim undertakes to do so; otherwise, it is not obligatory. However, if conveying the salams leads to harm (mafsadah), then the obligation to convey them is waived, even if one had undertaken to do so, based on the Prophet's (peace be upon him) saying: "There should be no harm nor reciprocating harm." And averting harms takes precedence over achieving benefits.