Ibrahim (may Allah have mercy on him) said: "If a person makes a bequest of one-third of his wealth, then acquires more wealth before dying, whatever has increased will also be counted as part of the one-third."
Hadith Referenceسنن سعید بن منصور / كتاب ولاية العصبة / 1546
Hadith Takhrij«أخرجه سعيد بن منصور فى «سننه» ترقيم الدرالسلفية برقم:، 369، وابن أبى شيبة فى «مصنفه» برقم: 31388»