Ch 2:
v.20: see v.4 - Timothy (Paul's 'trainee'/'apprentice') matches it
v.25: Epaphroditus got ill while serving Christ

Ch 3:
v.1: keep telling them until they get it
v.4: if anyone was going to put confidence in flesh (or status), Paul could
v.12-14: eternal perspective
v.15: any disagreement? take it to God
v.19: ...but we're NOT like that (or needn't or shouldn't be)

Ch 4:
Receive gifts graciously - as if from God