Exodus 24:3-8 describes the covenant ratification with blood sacrifice, the very event Psalm 50:5 alludes to — the saints made covenant by sacrifice.

Matthew 24:31 describes angels gathering the elect at Christ's return — a NT parallel to the gathering of saints here.

Matthew 26:28 presents Jesus instituting the new covenant in his blood, fulfilling the OT covenant sacrifice that gathers the saints.

1 Thessalonians 3:13 describes Christ coming with all His saints — directly echoing the gathering of saints in Psalm 50:5.

1 Thessalonians 4:16 describes the Lord's descent and the resurrection of the dead in Christ — a NT gathering parallel to Psalm 50:5.

1 Thessalonians 4:17 continues with believers caught up to meet the Lord — echoing the gathering of saints in Psalm 50:5.

2 Thessalonians 2:1 explicitly mentions 'our being gathered together to him' — a direct NT echo of gathering saints.

Hebrews 9:10-23 explains how old covenant sacrifices prefigure Christ's once-for-all sacrifice, the ultimate covenant by sacrifice.

Hebrews 12:24 mentions Jesus as mediator of a new covenant and his sprinkled blood, directly echoing the covenant sacrifice theme.

Hebrews 13:20 refers to the blood of the eternal covenant, connecting Christ's resurrection to the covenant sacrifice.

Genesis 15:9 shows Abram preparing animals for a covenant ceremony, another instance of making a covenant by sacrifice.

Zechariah 14:5 shows the Lord coming with all His saints — the gathering in Psalm 50:5 anticipates this eschatological assembly.

Isaiah 13:3 has God calling His sanctified ones for judgment — a parallel calling but for a different purpose.