Ṭarīf is wealth newly acquired by trade, earnings, or other means. Mutlad is longstanding property, especially what comes through inheritance. Their pairing gives a sense of comprehensive expenditure: both kinds of assets are included.
ExpressionSense
ṬarīfīMy recently acquired wealth
MutladīMy old or inherited wealth
Together, infāqī ṭarīfī wa-mutladī signals spending across the whole range of possessions, not merely making an occasional purchase.