It is better to go to the house of mourning, than to go to the house of feasting: for that is the end of all men; and the living will lay it to his heart. – Ecclesiastes 7:2

There have been many, many instances in which earnest Christian people have sought the conversion of their relatives or friends; they have prayed for them, and wept over them, and pleaded with them, but all their efforts have been unsuccessful; yet, after their death, the memory of their holy zeal has touched the conscience of the one who would not yield before, and brought him to Christ. I wish, dear friends, that your godly mother, who is in heaven, and who died leaving her son unsaved, might seem to come to you just now. I ask for no apparition, but that she may be consciously present to your mind, and that her dying words may ring in your ear, for perhaps the remembrance of what she said may be blessed to you even now. When I am taken away, I can but wish that any true and faithful word that I have spoken may still continue to speak to you from my grave. When good Mr. Payson died, he begged that his people might come and see him before he was interred; and those who did so read these words on his bosom, “Remember the word which I have spoken unto you being yet present with you.” It was thus his desire, you see, that he should have posthumous spiritual children, that they should be born to God even though they should seem to be born out of due time. Ah! you wives, who have been praying for your husbands these many years, never give them up, because they may be brought to Christ when you yourselves will be in heaven. Mothers and fathers, never cease pleading for your children, for they, too, may be brought to Jesus when you are among the angels…Persevere in prayer, you who are seeking the salvation of others. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/2663.cfm