What is the reward for the one who seeks Allah's reward (al-muhtasib) upon the death of his son by drowning, and how will this young one intercede for his parents?

Whoever loses a loved one from this world, and praises Allah, and says "To Allah we belong and to Him is our return" (استرجع), and seeks his reward from Allah, Allah will build for him a house in Paradise and call it "Bayt al-Hamd" (the House of Praise). This is based on the saying of the Prophet, peace and blessings be upon him: "When the child of a servant dies, Allah says to His angels: 'You have taken the child of My servant?' They say: 'Yes.' He says: 'You have taken the delight of his heart?' They say: 'Yes.' He says: 'What did My servant say?' They say: 'He praised You and said: "To Allah we belong and to Him is our return."' So Allah says: 'Build for My servant a house in Paradise and call it 'Bayt al-Hamd'." And children will intercede for their parents on the Day of Judgment.