Is the guardian entitled to reject a religious young man who proposed to his daughter because of old disagreements between the two families, despite the young man's religiosity and the current good relationship between the two families?

Muslims should end disagreements that cause resentment, especially if they are religious. If the guardian believes that marriage will remove enmity, he should marry off [his ward] due to the suitor's competence and strive to remove the enmity, as the Prophet, peace and blessings be upon him, said: "If someone whose religion and character you approve comes to you to seek marriage, then marry him. If you do not do so, there will be tribulation on earth and widespread corruption." However, if the guardian fears a renewal of disputes or ill-treatment of his daughter, he is permitted to refuse.